Biomaterial Database

Alpha-adrenoceptor subtypes in the coronary circulation. 1990

J Holtz

Institut für Angewandte Physiologie und Balneologie, Freiburg, FRG.

The pathophysiological role of sympathetic coronary innervation in myocardial ischemia is not clear, probably due to the complexities of adrenergic vascular control. In the canine coronary bed in vivo under beta-adrenergic blockade, alpha 1- as well as alpha 2-adrenoceptor-mediated constrictions can be elicited with predominance of the former in the epicardial conductance arteries, and of the latter in coronary resistance vessels. However, this distribution of functional responsiveness cannot indicate distribution of receptor density and cannot remain unchanged under differing conditions. First, each of these two classes of alpha-adrenoceptors consists of a mixture of different, interacting subtypes; second, the smooth muscular responsiveness to these two classes of alpha-adrenoceptors is differently modulated by contractile preactivation, by beta 2-blockade, and by the influence of sympathetic cotransmitters; third, alpha-adrenoceptors on endothelial cells and on sympathetic nerve endings can substantially modulate sympathetic coronary constriction. Thus, this neurogenic coronary control possesses a great functional plasticity, which is not yet fully evaluated with the presently available pharmacological tools.

UI	MeSH Term	Description	Entries
D011942	Receptors, Adrenergic, alpha	One of the two major pharmacological subdivisions of adrenergic receptors that were originally defined by the relative potencies of various adrenergic compounds. The alpha receptors were initially described as excitatory receptors that post-junctionally stimulate SMOOTH MUSCLE contraction. However, further analysis has revealed a more complex picture involving several alpha receptor subtypes and their involvement in feedback regulation.	Adrenergic alpha-Receptor,Adrenergic alpha-Receptors,Receptors, alpha-Adrenergic,alpha-Adrenergic Receptor,alpha-Adrenergic Receptors,Receptor, Adrenergic, alpha,Adrenergic alpha Receptor,Adrenergic alpha Receptors,Receptor, alpha-Adrenergic,Receptors, alpha Adrenergic,alpha Adrenergic Receptor,alpha Adrenergic Receptors,alpha-Receptor, Adrenergic,alpha-Receptors, Adrenergic
D003326	Coronary Circulation	The circulation of blood through the CORONARY VESSELS of the HEART.	Circulation, Coronary
D006321	Heart	The hollow, muscular organ that maintains the circulation of the blood.	Hearts
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D013564	Sympathetic Nervous System	The thoracolumbar division of the autonomic nervous system. Sympathetic preganglionic fibers originate in neurons of the intermediolateral column of the spinal cord and project to the paravertebral and prevertebral ganglia, which in turn project to target organs. The sympathetic nervous system mediates the body's response to stressful situations, i.e., the fight or flight reactions. It often acts reciprocally to the parasympathetic system.	Nervous System, Sympathetic,Nervous Systems, Sympathetic,Sympathetic Nervous Systems,System, Sympathetic Nervous,Systems, Sympathetic Nervous
D014661	Vasoconstriction	The physiological narrowing of BLOOD VESSELS by contraction of the VASCULAR SMOOTH MUSCLE.	Vasoconstrictions