Heterogeneous distribution of adrenergic receptors in coronary arteries and their influence on coronary arterial tone.
In-vitro experiments, using canine large (o.d. 1-2 mm) and small (o.d. 0.4-0.8mm) coronary arteries, were undertaken to determine the functional state of alpha- and beta-adrenergic receptors and their role in regulation of coronary arterial tone. Both large and small coronary arteries of the dog possess alpha and beta adrenergic receptors. Alpha-adrenergic receptors are more numerous on the circumflex vessel than elsewhere. Functionally, beta-adrenergic receptors appear to be dominant under physiological conditions in most types of coronary arteries. In canine coronary arteries, beta-adrenergic receptors have a greater affinity for noradrenaline than adrenaline. Alpha-adrenergic receptors have a greater affinity for adrenaline than noradrenaline. It is concluded that after beta-adrenergic blockade, in both large and small coronary arteries, alpha-adrenergic receptors play an important role in regulation of coronary arterial tone.
D000818:Animals; D003331:Coronary Vessels / Q000187:drug effects / Q000502:physiology*; D004285:Dogs; D004837:Epinephrine / Q000494:pharmacology; D005260:Female; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects / Q000502:physiology*; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000502:physiology*; D014661:Vasoconstriction / Q000187:drug effects
D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta; D010656:Phenylephrine; D011433:Propranolol; D007545:Isoproterenol; D009638:Norepinephrine; D004837:Epinephrine; D010646:Phentolamine