Biomaterial Database

Platelet-induced neurogenic coronary contractions due to accumulation of the false neurotransmitter, 5-hydroxytryptamine. 1985

R A Cohen

The purpose of this study was to determine if 5-hydroxytryptamine released from aggregating platelets could be accumulated and released by canine coronary adrenergic nerves, and if the false neurotransmitter resulted in an abnormal response of the smooth muscle to nerve stimulation. Isometric tension was measured in rings of epicardial coronary suspended in organ chambers filled with physiological salt solution. The response to electrical stimulation or exogenously added norepinephrine was elicited after contraction with prostaglandin F2 alpha. Electrical stimulation and exogenous norepinephrine caused beta-adrenergic relaxation of control rings. However, after rings were exposed for 2 h to aggregating platelets or 5-hydroxytryptamine, electrical stimulation caused frequency-dependent contractions. These contractions were prevented by the serotonergic antagonists, cyproheptadine or ketanserin, or by the neuronal uptake inhibitor, cocaine. The relaxation caused by exogenously added norepinephrine was unchanged after exposure to platelets or 5-hydroxytryptamine, indicating that smooth muscle alpha- and beta-adrenergic responsiveness was unchanged. The electrically stimulated overflow of radiolabeled norepinephrine from superfused strips of coronary artery was not altered by prior exposure to 5-hydroxytryptamine, indicating that the effect of exposure on the response to electrical stimulation is primarily at smooth muscle serotonergic receptors. Canine coronary arteries accumulated and metabolized radiolabeled 5-hydroxytryptamine in vitro. The accumulation of 5-hydroxytryptamine was inhibited by cocaine or by adrenergic denervation with 6-hydroxydopamine but unaffected by removal of endothelium, indicating that the adrenergic nerves were the primary site of accumulation. Electrical stimulation of superfused strips of coronary artery preincubated with radiolabeled 5-hydroxytryptamine caused the release of the intact indoleamine; this was blocked by the neurotoxin, tetrodotoxin. These studies suggest that 5-hydroxytryptamine liberated from aggregating platelets may be accumulated by coronary adrenergic nerve endings. Upon its release from the nerves as a false transmitter, the amine can activate serotonergic receptors on the smooth muscle and reverse the action of the adrenergic nerves from dilator to constrictor.

UI	MeSH Term	Description	Entries
D009130	Muscle, Smooth	Unstriated and unstriped muscle, one of the muscles of the internal organs, blood vessels, hair follicles, etc. Contractile elements are elongated, usually spindle-shaped cells with centrally located nuclei. Smooth muscle fibers are bound together into sheets or bundles by reticular fibers and frequently elastic nets are also abundant. (From Stedman, 25th ed)	Muscle, Involuntary,Smooth Muscle,Involuntary Muscle,Involuntary Muscles,Muscles, Involuntary,Muscles, Smooth,Smooth Muscles
D009200	Myocardial Contraction	Contractile activity of the MYOCARDIUM.	Heart Contractility,Inotropism, Cardiac,Cardiac Inotropism,Cardiac Inotropisms,Contractilities, Heart,Contractility, Heart,Contraction, Myocardial,Contractions, Myocardial,Heart Contractilities,Inotropisms, Cardiac,Myocardial Contractions
D009638	Norepinephrine	Precursor of epinephrine that is secreted by the ADRENAL MEDULLA and is a widespread central and autonomic neurotransmitter. Norepinephrine is the principal transmitter of most postganglionic sympathetic fibers, and of the diffuse projection system in the brain that arises from the LOCUS CERULEUS. It is also found in plants and is used pharmacologically as a sympathomimetic.	Levarterenol,Levonorepinephrine,Noradrenaline,Arterenol,Levonor,Levophed,Levophed Bitartrate,Noradrenaline Bitartrate,Noradrénaline tartrate renaudin,Norepinephrin d-Tartrate (1:1),Norepinephrine Bitartrate,Norepinephrine Hydrochloride,Norepinephrine Hydrochloride, (+)-Isomer,Norepinephrine Hydrochloride, (+,-)-Isomer,Norepinephrine d-Tartrate (1:1),Norepinephrine l-Tartrate (1:1),Norepinephrine l-Tartrate (1:1), (+,-)-Isomer,Norepinephrine l-Tartrate (1:1), Monohydrate,Norepinephrine l-Tartrate (1:1), Monohydrate, (+)-Isomer,Norepinephrine l-Tartrate (1:2),Norepinephrine l-Tartrate, (+)-Isomer,Norepinephrine, (+)-Isomer,Norepinephrine, (+,-)-Isomer
D010974	Platelet Aggregation	The attachment of PLATELETS to one another. This clumping together can be induced by a number of agents (e.g., THROMBIN; COLLAGEN) and is part of the mechanism leading to the formation of a THROMBUS.	Aggregation, Platelet
D001792	Blood Platelets	Non-nucleated disk-shaped cells formed in the megakaryocyte and found in the blood of all mammals. They are mainly involved in blood coagulation.	Platelets,Thrombocytes,Blood Platelet,Platelet,Platelet, Blood,Platelets, Blood,Thrombocyte
D003042	Cocaine	An alkaloid ester extracted from the leaves of plants including coca. It is a local anesthetic and vasoconstrictor and is clinically used for that purpose, particularly in the eye, ear, nose, and throat. It also has powerful central nervous system effects similar to the amphetamines and is a drug of abuse. Cocaine, like amphetamines, acts by multiple mechanisms on brain catecholaminergic neurons; the mechanism of its reinforcing effects is thought to involve inhibition of dopamine uptake.	Cocaine HCl,Cocaine Hydrochloride,HCl, Cocaine,Hydrochloride, Cocaine
D003331	Coronary Vessels	The veins and arteries of the HEART.	Coronary Arteries,Sinus Node Artery,Coronary Veins,Arteries, Coronary,Arteries, Sinus Node,Artery, Coronary,Artery, Sinus Node,Coronary Artery,Coronary Vein,Coronary Vessel,Sinus Node Arteries,Vein, Coronary,Veins, Coronary,Vessel, Coronary,Vessels, Coronary
D004285	Dogs	The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)	Canis familiaris,Dog
D004558	Electric Stimulation	Use of electric potential or currents to elicit biological responses.	Stimulation, Electric,Electrical Stimulation,Electric Stimulations,Electrical Stimulations,Stimulation, Electrical,Stimulations, Electric,Stimulations, Electrical
D004727	Endothelium	A layer of epithelium that lines the heart, blood vessels (ENDOTHELIUM, VASCULAR), lymph vessels (ENDOTHELIUM, LYMPHATIC), and the serous cavities of the body.	Endotheliums