Vasodilation

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Vasodilation

Vasodilation refers to the widening of blood vessels resulting from relaxation of smooth muscle

Smooth muscle

Smooth muscle is a type of non-striated muscle, found within the tunica media layer of large and small arteries and veins, the urinary bladder, uterus, male and female reproductive tracts, gastrointestinal tract, respiratory tract, the ciliary muscle, and iris of the eye....
cells within the vessel walls, particularly in the large arteries, smaller arterioles and large veins. The process is essentially the opposite of vasoconstriction

Vasoconstriction

Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, particularly the large arteries, arterioles and veins....
, or the narrowing of blood vessels. When vessels dilate, the flow of blood is increased due to a decrease in vascular resistance

Vascular resistance

Vascular resistance is a term used to define the resistance to flow that must be overcome to push blood through the circulatory system. The resistance offered by the peripheral circulation is known as the systemic vascular resistance , while the resistance offered by the vasculature of the lungs is known as the pulmonary vascular re...
. Therefore, dilation of arterial blood vessels (mainly arterioles) leads to a decrease in blood pressure

Blood pressure

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Encyclopedia

Vasodilation refers to the widening of blood vessels resulting from relaxation of smooth muscle

Smooth muscle

Vasoconstriction

Vascular resistance

Blood pressure

Blood pressure is the pressure exerted by circulating blood on the walls of blood vessels, and constitutes one of the principal vital signs. The pressure of the circulating blood decreases as it moves away from the heart through artery and capillary, and toward the heart through veins....
. The response may be intrinsic (due to local processes in the surrounding tissue) or extrinsic (due to hormones or the nervous system

Nervous system

The nervous system is a Neural network of specialized cells that communicate information about an animal's surroundings and itself. It processes this information and causes reactions in other parts of the body....
). Additionally, the response may either be localized to a specific organ (depending on the metabolic needs of a particular tissue, as during strenuous exercise), or systemic (seen throughout the entire systemic circulation

Systemic circulation

Systemic circulation is the portion of the cardiovascular system which carries oxygenated blood away from the heart, to the body, and returns deoxygenated blood back to the heart....
). Factors that result in vasodilation are termed vasodilators.

Function

Vasodilation directly affects the relationship between mean arterial pressure

Mean arterial pressure

The mean arterial pressure is a term used in medicine to describe a notional average blood pressure in an individual. It is defined as the average arterial pressure during a single cardiac cycle....
, cardiac output

Cardiac output

Cardiac output is the volume of blood being pumped by the heart, in particular by a ventricle in a minute. This is measured in dm3 min-1 ....
and total peripheral resistance

Total peripheral resistance

Vasculature throughout the entire body can be thought of as two separate circuits - one is the systemic circulation, while the other is the pulmonary circulation....
(TPR). The cardiac output (blood flow measured in volume per unit time) is equal to the heart rate

Heart rate

Heart rate is a measure of the number of heart beats per minute . The average resting human heart rate is about 70 bpm for adult males and 75 bpm for adult females....
(in beats per unit time) multiplied by the stroke volume

Stroke volume

In cardiovascular physiology, stroke volume is the volume of blood pumped from one ventricles of the heart of the heart with each beat. It is calculated by subtracting the volume of blood in the ventricle at the end of a beat from the volume of blood just prior to the beat ....
(the volume of blood ejected during ventricular systole

Systole

Systole can mean the following:*Systole is a term describing the contraction of the heart.*Systolic geometry is a term used in mathematics....
). TPR depends on several factors including the length of the vessel, the viscosity of blood (determined by hematocrit

Hematocrit

The hematocrit or packed cell volume or erythrocyte volume fraction is the proportion of blood volume that is occupied by red blood cells....
) and the diameter of the blood vessel. The latter is the most important variable in determining resistance, changing by the fourth power of the radius, in accordance with Poiseuille's Law. An increase in either of these physiological components (cardiac output or TPR) cause a rise in the mean arterial pressure. Vasodilation works to decrease TPR and blood pressure through relaxation of smooth muscle cells in the tunica media

Tunica media

The tunica media is the middle layer of an artery or vein....
layer of large arteries and smaller arterioles.

Vasodilation occurs in superficial blood vessels of warm-blooded animals when their ambient environment is hot; this process diverts the flow of heated blood to the skin of the animal, where heat can be more easily released into the atmosphere. The opposite physiological process is vasoconstriction

Vasoconstriction

Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, particularly the large arteries, arterioles and veins....
. These processes are naturally modulated by local paracrine agents from endothelial cells (e.g nitric oxide

Nitric oxide

Nitric oxide or nitrogen monoxide is a chemical compound with chemical formula NitrogenOxygen. This gas is an important signaling molecule in the body of mammals, including humans, and is an extremely important intermediate in the chemical industry....
, bradykinin

Bradykinin

Bradykinin is a nonapeptide that causes blood vessels to enlarge , and therefore causes blood pressure to lower. A class of drugs called ACE inhibitors, which are used to lower blood pressure, increase bradykinin further lowering blood pressure....
, potassium ions and adenosine

Adenosine

Adenosine is a nucleoside composed of a molecule of adenine attached to a ribose sugar molecule moiety via a ?-N9-glycosidic bond....
), as well as an organism's Autonomic Nervous System

Autonomic nervous system

The autonomic nervous system is the part of the peripheral nervous system that acts as a control system, maintaining human homeostasis in the body....
and adrenal gland

Adrenal gland

In mammals, the adrenal glands are the star-shaped endocrine glands that sit on top of the kidneys; their name indicates that position . They are chiefly responsible for regulating the stress response through the biosynthesis of corticosteroids and catecholamines, including cortisol and adrenaline, respectively....
s, both of which secrete catecholamines such as norepinephrine

Norepinephrine

Norepinephrine or noradrenaline is a catecholamine with dual roles as a hormone and a neurotransmitter.As a stress hormone, norepinephrine affects parts of the brain where attention and responding actions are controlled....
and epinephrine

Epinephrine

Epinephrine is a hormone and neurotransmitter.Epinephrine increases the "fight or flight" response of the Sympathetic nervous system of the autonomic nervous system....
, respectively.

Examples and individual mechanisms

Vasodilation is the result of relaxation in smooth muscle

Smooth muscle

Smooth muscle is a type of non-striated muscle, found within the tunica media layer of large and small arteries and veins, the urinary bladder, uterus, male and female reproductive tracts, gastrointestinal tract, respiratory tract, the ciliary muscle, and iris of the eye....
surrounding the blood vessels. This relaxation, in turn, relies on removing the stimulus for contraction, which depends on intracellular calcium ion concentrations and, consequently, phosphorylation

Phosphorylation

Phosphorylation is the addition of a phosphate group to a protein or other organic molecule. Protein phosphorylation in particular plays a significant role in a wide range of cellular processes....
of the light chain of the contractile protein myosin

Myosin

Myosins are a large family of motor proteins found in eukaryotic Biological tissue. They are responsible for actin-based motility.Following the discovery, by Pollard and Korn, of enzymes with myosin-like function in Acanthamoeba, a large number of divergent myosin genes have been discovered throughout eukaryotes....
. Thus, vasodilation mainly works either by lowering intracellular calcium concentration or the dephosphorylation of myosin. This includes stimulation of myosin light chain phosphatase and induction of calcium symporters and antiporters that pump calcium ions out of the intracellular compartment. This is accomplished through reuptake of ions into the sarcoplasmic reticulum via exchangers and expulsion across the plasma membrane. There are three main intracellular stimuli that can result in the vasodilation of blood vessels. The specific mechanism to accomplish these effects vary from vasodilator to vasodilator.

Class	Description	Example
Hyperpolarization Hyperpolarization Hyperpolarization has several meanings:* Hyperpolarization occurs when the strength of the electric field across the width of a cell membrane increases... mediated (Calcium channel blocker Calcium channel blocker Calcium channel blockers are a class of medication and natural substances which disrupt the conduction of calcium channels.It has effects on many excitable cells of the body, such as cardiac muscle, i.e.... )	Changes in the resting membrane potential of the cell affects the level of intracellular calcium through modulation of voltage sensitive calcium channels in the plasma membrane.	adenosine Adenosine Adenosine is a nucleoside composed of a molecule of adenine attached to a ribose sugar molecule moiety via a ?-N9-glycosidic bond....
cAMP CAMP CAMP may stand for:* Cyclic adenosine monophosphate * Cathelicidin* Campaign Against Marijuana Planting* Central Atlantic Magmatic Province... mediated	Adrenergic Adrenergic An adrenergic is a medication, or other substance, which has effects similar to, or the same as, epinephrine . Thus, they are a kind of sympathomimetic agents.... stimulation results in elevated levels of cAMP and protein kinase A, which results in increasing calcium removal from the cytoplasm	prostacyclin Prostacyclin Prostacyclin is a member of the family of lipid molecules known as eicosanoids.As a drug, it is also known as "epoprostenol". The terms are sometimes used interchangeably....
cGMP CGMP CGMP is an initialism. It can refer to;cyclic guanosine monophosphate current good manufacturing practice The Cisco Systems version of the Internet Group Management Protocol snooping computer networking protocol... mediated (Nitrovasodilator Nitrovasodilator A nitrovasodilator* is an agent which causes vasodilation by donation of nitric oxide.Examples include nitroprusside and nitroglycerine.... )	Through stimulation of protein kinase G	nitric oxide Nitric oxide Nitric oxide or nitrogen monoxide is a chemical compound with chemical formula NitrogenOxygen. This gas is an important signaling molecule in the body of mammals, including humans, and is an extremely important intermediate in the chemical industry....

PDE5 inhibitor

A phosphodiesterase type 5 inhibitor, often shortened to PDE5 inhibitor, is a medication used to block the degradative action of phosphodiesterase type 5 on cyclic GMP in the smooth muscle cells lining the blood vessels supplying the corpus cavernosum of the penis....
s and potassium channel opener

Potassium channel opener

A potassium channel opener is a drug that facilitates the transmission through a potassium channel.An example is minoxidil.Other examples include:...
s can also have similar results.

Compounds that mediate the above mechanisms may be grouped as endogenous

Endogenous

The word endogenous means "arising from within", the opposite of exogenous....
and exogenous

Exogenous

Exogenous refers to an action or object coming from outside a system. It is the opposite of endogenous, something generated from within the system....
.

Endogenous

Vasodilators	Receptor (? = opens. ? = closes)	Transduction (? = increases. ? = decreases)
EDHF	?	hyperpolarization Hyperpolarization Hyperpolarization has several meanings:* Hyperpolarization occurs when the strength of the electric field across the width of a cell membrane increases... --> ?VDCC Voltage-dependent calcium channel Voltage-dependent calcium channels are a group of voltage-gated ion channel ion channels found in excitable cells with a Permeability to the ion calcium.... --> ?intracellular Ca²⁺
depolarization Depolarization In biology, depolarization is a decrease in the absolute value of a cell's membrane potential. Thus, changes in membrane voltage in which the membrane potential becomes less positive or less negative are both depolarizations....	?Voltage-gated K⁺ channel
interstitial Interstitial fluid Interstitial fluid is a solution which bathes and surrounds the cells of multicellular animals. It is the main component of the extracellular fluid, which also includes Blood plasma and transcellular fluid.... K⁺ Potassium Potassium is a chemical element. It has the symbol K , atomic number 19, and atomic mass 39.0983. Potassium was first isolated from potash, hence the name....	directly
nitric oxide Nitric oxide Nitric oxide or nitrogen monoxide is a chemical compound with chemical formula NitrogenOxygen. This gas is an important signaling molecule in the body of mammals, including humans, and is an extremely important intermediate in the chemical industry....	?NO receptor	?cGMP --> ?PKG activity --> phosphorylation of MLCK --> ?MLCK activity --> dephosphorylation of MLC ?SERCA SERCA SERCA stands for sarcoplasmic reticulum/endoplasmic reticulum Calcium2+-ATPase. It is a P-ATPase#P-ATPase of the calcium ATPase type.... --> ?intracellular Ca²⁺
ß2 adrenergic agonists Beta-2 adrenergic receptor The beta-2 adrenergic receptor , also known as ADRB2, is an beta-adrenergic receptor, and also denotes the human gene encoding it....	ß-2 adrenergic receptor Beta-2 adrenergic receptor The beta-2 adrenergic receptor , also known as ADRB2, is an beta-adrenergic receptor, and also denotes the human gene encoding it....	?G_s Gs alpha subunit The Gs alpha subunit is a heterotrimeric G protein subunit which activates adenylate cyclase. Researchers have discovered that a change in the location of this protein in the brain could serve as a biomarker for depression, allowing a simple, rapid, laboratory test to identify patients with depression.... activity --> ?AC Adenylate cyclase Adenylate cyclase is a lyase enzyme.... activity --> ?cAMP --> ?PKA activity --> phosphorylation of MLCK --> ?MLCK activity --> dephosphorylation of MLC
histamine Histamine Histamine is a biogenic amine involved in local immune system as well as regulating physiological function in the gut and acting as a neurotransmitter....	Histamine H1 receptor
prostacyclin Prostacyclin Prostacyclin is a member of the family of lipid molecules known as eicosanoids.As a drug, it is also known as "epoprostenol". The terms are sometimes used interchangeably....	IP receptor
Prostaglandin D₂	DP receptor
Prostaglandin E₂	EP receptor
VIP Vasoactive intestinal peptide Vasoactive intestinal peptide is a peptide hormone containing 28 amino acid residue s and is produced in many areas of the human body including the gut, pancreas and suprachiasmatic nuclei of the hypothalamus in the brain....	VIP receptor Vasoactive intestinal peptide receptor There are two known receptors for the vasoactive intestinal peptide termed VPAC1 and VPAC2. These receptors bind both VIP and pituitary adenylate cyclase-activating polypeptide to some degree....	?G_s Gs alpha subunit The Gs alpha subunit is a heterotrimeric G protein subunit which activates adenylate cyclase. Researchers have discovered that a change in the location of this protein in the brain could serve as a biomarker for depression, allowing a simple, rapid, laboratory test to identify patients with depression.... activity --> ?AC Adenylate cyclase Adenylate cyclase is a lyase enzyme.... activity --> ?cAMP --> ?PKA activity --> phosphorylation of MLCK --> ?MLCK activity --> dephosphorylation of MLC open Ca²⁺-activated Calcium-activated potassium channel Calcium-activated potassium channels are divided into BK channels, IK channels, and SK channels based on their conductance .This family of ion channels is, for the most part, activated by intracellular Ca2+ and contains 8 members.... and voltage-gated K⁺channel Voltage-gated potassium channel Voltage-gated potassium channels are potassium channel and Voltage-gated ion channel in the cell's membrane potential. They play a crucial role during action potentials in returning the depolarized cell to a resting state.... s --> hyperpolarization --> close VDCC Voltage-dependent calcium channel Voltage-dependent calcium channels are a group of voltage-gated ion channel ion channels found in excitable cells with a Permeability to the ion calcium.... --> ?intracellular Ca²⁺
(extracellular) adenosine Adenosine Adenosine is a nucleoside composed of a molecule of adenine attached to a ribose sugar molecule moiety via a ?-N9-glycosidic bond....	A₁, A_2a Adenosine A2A receptor The adenosine A2A receptor, also known as ADORA2A, is an adenosine receptor, but also denotes the human gene encoding it.... and A_2b Adenosine A2b receptor The adenosine A2b receptor, also known as ADORA2B, is an adenosine receptor, and also denotes the human gene incoding it.... adenosine receptors	?ATP-sensitive K⁺ channel --> hyperpolarization --> close VDCC Voltage-dependent calcium channel Voltage-dependent calcium channels are a group of voltage-gated ion channel ion channels found in excitable cells with a Permeability to the ion calcium.... --> ?intracellular Ca²⁺
(extracellular) ATP Adenosine triphosphate This article is about the chemical used by cells as an energy carrier. For other uses, see ATP .Adenosine-5'-triphosphate is a multifunctional nucleotide, and plays an important role in cell biology as a coenzyme that is the "molecule unit of currency" of intracellular energy transfer.... (extracellular) ADP Adenosine diphosphate Adenosine diphosphate, abbreviated ADP, is a nucleotide. It is an ester of pyrophosphoric acid with the nucleoside adenosine. ADP consists of the pyrophosphate Functional group, the pentose sugar ribose, and the nucleobase adenine....	?P2Y receptor P2Y receptor P2Y receptors are a family of purinergic receptors, G protein-coupled receptors stimulated by nucleotides such as Adenosine triphosphate, Adenosine diphosphate, Uridine triphosphate, Uridine diphosphate and UDP-glucose....	activate G_q Gq alpha subunit Gq protein or Gq/11 is a heterotrimeric G protein subunit that activates phospholipase C . PLC in turn hydrolyzes phosphatidylinositol to diacyl glycerol and inositol triphosphate signal transduction Metabolic pathway.... --> ?PLC Phospholipase C Phosphoinositide phospholipase C is a family of eukaryotic intracellular enzymes that play an important role in signal transduction processes.... activity --> ?intracellular Ca²⁺ --> ?NOS Nitric oxide synthase Nitric oxide synthases are present among eukaryotic enzymes as dimeric, calmodulin-dependent or calmodulin-containing cytochrome p450-like hemoprotein that combine reductase and oxygenase catalytic domains in one dimer, bear both flavin adenine dinucleotide and flavin mononucleotide , and carry out a 5`-electron oxidation of non-aromatic a... activity --> ?NO Nitric oxide Nitric oxide or nitrogen monoxide is a chemical compound with chemical formula NitrogenOxygen. This gas is an important signaling molecule in the body of mammals, including humans, and is an extremely important intermediate in the chemical industry.... --> (see nitric oxide)
L-Arginine Arginine Arginine is an a-amino acid. The Optical isomerism is one of the 20 most common natural amino acids. Its codons are CGU, CGC, CGA, CGG, AGA, and AGG....	imidazoline Imidazoline receptor Imidazoline receptors are receptor s for clonidine and other imidazolines.ClassesThere are three classes of imidazoline receptors:... and a-2 receptor Alpha-2 adrenergic receptor The a2 receptor is a type of adrenergic receptor.... ?	G_i Gi alpha subunit Gi alpha subunit is a heterotrimeric G protein subunit which inhibits the production of Cyclic_adenosine_monophosphate from Adenosine triphosphate.... --> ?cAMP --> activation of Na⁺/K⁺-ATPase Na+/K+-ATPase Na+/K+-ATPase is an enzyme located in the plasma membrane . It is found in the human cell and is found in all metazoa .... --> ?intracellular Na²⁺ Sodium Sodium is an element which has the symbol Na , atomic number 11, atomic mass 23 amu , and a common oxidation number +1. Sodium is a soft, silvery white, highly reactive element and is a member of the alkali metals within "group 1" .... --> ?Na⁺/Ca²⁺ exchanger Sodium-calcium exchanger The sodium-calcium exchanger is an antiporter membrane protein which removes calcium from cells. It uses the energy that is stored in the electrochemical gradient of sodium by allowing Na+ to flow down its gradient across the plasma membrane in exchange for the countertransport of calcium in biology ions .... activity --> ?intracellular Ca²⁺
Bradykinin Bradykinin Bradykinin is a nonapeptide that causes blood vessels to enlarge , and therefore causes blood pressure to lower. A class of drugs called ACE inhibitors, which are used to lower blood pressure, increase bradykinin further lowering blood pressure....	Bradykinin receptor Bradykinin receptor The bradykinin receptor family is a group of G-protein coupled receptors whose principal ligand is the protein bradykinin.There are two Bradykinin receptors: the bradykinin receptor B1 and the bradykinin receptor B2....
Substance P Substance P In the field of neuroscience, substance P is a neuropeptide: an undecapeptide that functions as a neurotransmitter and as a neuromodulator which alters the excitability of the dorsal horn ganglion ....
Niacin Niacin Niacin, also known as vitamin B3, is a water-soluble vitamin which prevents the Nutrition disorder pellagra. It is an organic compound with the chemical formula C6H5NO2.... (nicotinic acid)
Platelet activating factor (PAF)
CO₂ Carbon dioxide Carbon dioxide is a chemical compound composed of two oxygen atoms covalent bond to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state....	-	?interstitial Interstitial fluid Interstitial fluid is a solution which bathes and surrounds the cells of multicellular animals. It is the main component of the extracellular fluid, which also includes Blood plasma and transcellular fluid.... pH PH pH is a measure of the Acid or Base of a solution. It is defined as the cologarithm of the Activity of dissolved hydrogen ions . Hydrogen ion activity coefficients cannot be measured experimentally, so they are based on theoretical calculations.... --> ?
(probably) interstitial Interstitial fluid Interstitial fluid is a solution which bathes and surrounds the cells of multicellular animals. It is the main component of the extracellular fluid, which also includes Blood plasma and transcellular fluid.... lactic acid Lactic acid Lactic acid , also known as milk acid, is a chemical compound that plays a role in several biochemistry processes. It was first isolated in 1780 by a Swedish chemist, Carl Wilhelm Scheele, and is a carboxylic acid with a chemical formula of C3H6O3....	-
muscle work	-	?vasodilators: ?ATP Adenosine triphosphate This article is about the chemical used by cells as an energy carrier. For other uses, see ATP .Adenosine-5'-triphosphate is a multifunctional nucleotide, and plays an important role in cell biology as a coenzyme that is the "molecule unit of currency" of intracellular energy transfer.... consumption --> ?adenosine Adenosine Adenosine is a nucleoside composed of a molecule of adenine attached to a ribose sugar molecule moiety via a ?-N9-glycosidic bond.... ?glucose Glucose Glucose , a monosaccharide also known as grape sugar, blood sugar, or corn sugar, is a very important carbohydrate in biology.... usage --> CO₂ Carbon dioxide Carbon dioxide is a chemical compound composed of two oxygen atoms covalent bond to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state.... ?interstitial Interstitial fluid Interstitial fluid is a solution which bathes and surrounds the cells of multicellular animals. It is the main component of the extracellular fluid, which also includes Blood plasma and transcellular fluid.... K⁺ Sodium Sodium is an element which has the symbol Na , atomic number 11, atomic mass 23 amu , and a common oxidation number +1. Sodium is a soft, silvery white, highly reactive element and is a member of the alkali metals within "group 1" .... ?(extracellular) ATP Adenosine triphosphate This article is about the chemical used by cells as an energy carrier. For other uses, see ATP .Adenosine-5'-triphosphate is a multifunctional nucleotide, and plays an important role in cell biology as a coenzyme that is the "molecule unit of currency" of intracellular energy transfer.... ?(extracellular) ADP Adenosine diphosphate Adenosine diphosphate, abbreviated ADP, is a nucleotide. It is an ester of pyrophosphoric acid with the nucleoside adenosine. ADP consists of the pyrophosphate Functional group, the pentose sugar ribose, and the nucleobase adenine.... ?interstitial Interstitial fluid Interstitial fluid is a solution which bathes and surrounds the cells of multicellular animals. It is the main component of the extracellular fluid, which also includes Blood plasma and transcellular fluid.... K⁺ Sodium Sodium is an element which has the symbol Na , atomic number 11, atomic mass 23 amu , and a common oxidation number +1. Sodium is a soft, silvery white, highly reactive element and is a member of the alkali metals within "group 1" .... ?vasoconstrictors: ?ATP Adenosine triphosphate This article is about the chemical used by cells as an energy carrier. For other uses, see ATP .Adenosine-5'-triphosphate is a multifunctional nucleotide, and plays an important role in cell biology as a coenzyme that is the "molecule unit of currency" of intracellular energy transfer.... consumption --> ? ATP (intracellular) ?oxygen Oxygen Oxygen no O2 produced; 2) O2 produced, but absorbed in oceans & seabed rock; 3) O2 starts to gas out of the oceans, but is absorbed by land surfaces and formation of ozone layer; 4-5) O2 sinks filled and the gas accumulates]]... --> ?oxidative phosphorylation Oxidative phosphorylation Oxidative phosphorylation is a metabolic pathway that uses energy released by the redox of nutrients to produce adenosine triphosphate . Although the many forms of life on earth use a range of different nutrients, almost all carry out oxidative phosphorylation to produce ATP, the molecule that supplies energy to metabolism.... --> ? ATP (intracellular)

Exogenous vasodilators

Absence of high levels of environmental noise
Absence of high levels of illumination
Over-illumination

Over-illumination is the presence of lighting intensity beyond that required for a specified activity. Over-illumination was commonly ignored between 1950 and 1995, especially in office and retail environments; only since then has the interior design community begun to reconsider this practice....
Adenocard - Adenosine agonist, primarily used as an anti-arrhythmic.
Alpha blocker
Alpha blocker

Alpha-1 blockers constitute a variety of drugs which block Adrenergic receptor#Alpha .CE.B1 receptors in arteries and smooth muscles....
s (block the vasoconstricting effect of adrenaline).
Amyl nitrite
Amyl nitrite

Amyl nitrite is the chemical compound with the chemical formula C5H11ONO. A variety of isomers are known, but they all feature an amyl group attached to the nitrito functional group....
and other nitrites are often used recreationally as a vasodilator, causing lightheadedness and a euphoric feeling.
Atrial natriuretic peptide
Atrial natriuretic peptide

Atrial natriuretic peptide , atrial natriuretic factor , atrial natriuretic hormone , or atriopeptin, is a weak vasodilator, and a protein hormone secreted by heart muscle cells....
(ANP) - a weak vasodilator.
Ethanol
Ethanol

Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatility , flammable, colorless liquid....
Histamine-inducers

Complement
Complement system

The complement system is a biochemical cascade that helps clear pathogens from an organism. It is part of the larger immune system that is not adaptable and does not change over the course of an individual's lifetime; as such it belongs to the innate immunity....
proteins C3a, C4a and C5a work by triggering histamine release from mast cell
Mast cell

A mast cell is a resident cell of several types of tissues and contains many Granule rich in histamine and heparin. Although best known for their role in allergy and anaphylaxis, mast cells play an important protective role as well, being intimately involved in wound healing and defense against pathogens....
s and basophil granulocyte
Basophil granulocyte

Basophils are the least common of the granulocytes, representing about 0.01% to 0.3% of circulating leukocytes .The name comes from the fact that these leucocytes are basophilic, i.e., they are susceptible to staining by base dyes, as shown in the picture....
s.

Nitric oxide inducers

Glyceryl trinitrate
Glyceryl trinitrate (pharmacology)

Glyceryl trinitrate is an alternate name for the chemical nitroglycerine, which has been used to treat Angina pectoris and heart failure since at least 1870....
(commonly known as Nitroglycerin
Nitroglycerin

Nitroglycerin , also known as nitroglycerine, , trinitroglycerin, trinitroglycerine, 1,2,3-trinitroxypropane and glyceryl trinitrate, is a heavy, colorless, oily, explosive liquid obtained by nitration glycerol....
)
Isosorbide mononitrate
Isosorbide mononitrate

Isosorbide mononitrate is a drug used principally in the treatment of angina pectoris and acts by dilating the blood vessels so as to reduce the blood pressure....
& Isosorbide dinitrate
Isosorbide dinitrate

Isosorbide dinitrate is a nitrate used pharmacology as a vasodilation, e.g. in angina pectoris but also for anal fissure, a condition which is known to involve decreased blood supply leading to poor healing....
Pentaerythritol Tetranitrate
PETN

Pentaerythritol tetranitrate is one of the most powerful explosive material known, with a relative effectiveness factor of 1.66....
(PETN)
Sodium nitroprusside
Sodium nitroprusside

Sodium nitroprusside is the chemical compound with the chemical formula Na2[Fe5NO]?2H2O. This salt serves as a source of nitric oxide, a potent peripheral vasodilator that affects both arterioles and venules ....
PDE5 inhibitor
PDE5 inhibitor

A phosphodiesterase type 5 inhibitor, often shortened to PDE5 inhibitor, is a medication used to block the degradative action of phosphodiesterase type 5 on cyclic GMP in the smooth muscle cells lining the blood vessels supplying the corpus cavernosum of the penis....
s: these agents indirectly increase the effects of nitric oxide

Sildenafil
Sildenafil

Sildenafil citrate, sold as Viagra, Revatio and under various other trade names, is a Medication used to treat erectile dysfunction and pulmonary hypertension ....
(Viagra)
Tadalafil
Tadalafil

Tadalafil is an orally administered medication for treating erectile dysfunction , that initially was developed by the biotechnology company ICOS, and then again developed and marketed world-wide as Cialis, by Lilly ICOS, LLC, the joint venture of ICOS Corporation and Eli Lilly and Company....
Vardenafil
Vardenafil

Vardenafil is a PDE5 inhibitor used for treating impotence that is sold under the trade name Levitra , , ....

Tetrahydrocannabinol
Tetrahydrocannabinol

Tetrahydrocannabinol , also known as THC, ?9-THC, ?9-tetrahydrocannabinol, ?1-tetrahydrocannabinol , or dronabinol, is the main psychoactive substance found in the Cannabis plant....
(THC) - the major active chemical in marijuana
Medical cannabis

Medical cannabis refers to the use of the Cannabis plant as a physician-recommended Cannabis or herbal therapy as well as synthetic THC and cannabinoids....
. Its mild vasodilating effects redden the eyes of cannabis
Cannabis (drug)

Cannabis, also known as Marijuana or marihuana, or ganja , is a psychoactive drug extracted from the plant Cannabis sativa, or more often, Cannabis sativa subsp....
users.
Theobromine
Theobromine

Theobromine, also known as xantheose, is a bitter alkaloid of the cacao plant, found in chocolate, as well as in a number of chocolate-free foods made from theobromine sources including the leaves of the tea plant, the kola or cola nut, and acai berries....
.
Papaverine
Papaverine

Papaverine is an opium alkaloid used primarily in the treatment of visceral spasm, vasospasm , and occasionally in the treatment of erectile dysfunction....
an alkaloid found in the opium poppy papaver somniferum

Therapeutic uses

Vasodilators are used to treat conditions such as hypertension

Hypertension

Hypertension, also referred to as high blood pressure, HTN or HPN, is a medical condition in which the blood pressure is chronically elevated....
, where the patient has an abnormally high blood pressure, as well as angina and congestive heart failure

Congestive heart failure

Heart failure is a condition in which a problem with the structure or function of the heart impairs its ability to supply sufficient blood flow to meet the body's needs....
, where maintaining a lower blood pressure reduces the patient's risk of developing other cardiac problems. Flushing

Flushing (physiology)

For a person to flush is to become markedly red in the face and often other areas of the skin, from various physiology conditions. Flushing is generally distinguished, despite a close physiological relation between them, from blushing, which is milder, generally restricted to the face or cheeks, and generally assumed to reflect embarrassment....
may be a physiological response to vasodilators. Viagra, a phosphodiesterase

Phosphodiesterase

A phosphodiesterase is any enzyme that breaks a phosphodiester bond. Usually, people speaking of phosphodiesterase are referring to cyclic nucleotide phosphodiesterases, which have great clinical significance and are described below....
inhibitor, works to increase blood flow in the penis through vasodilation. It may also be used to treat pulmonary arterial hypertension (PAH).