Beta2-adrenoceptors facilitating noradrenaline secretion from human vasoconstrictor nerves.
Isolated biopsy specimens of human peripheral arteries and veins, preincubated with 3H-(-)- noradrenaline (NA) to label the neural stores of NA, were used to study the Beta-adrenoceptors previously found to increase the secretion of 3H-NA evoked by electrical field stimulation of the adrenergic nerves of this tissue. The increase in nerve stimulation induced secretion of 3H-NA caused by 0.04 muM isoprenaline was prevented by 1 muM propranolol. This beta-blocking drug by itself slightly but significantly depressed the secretion of 3H-NA caused by nerve stimulation in the absence of isoprenaline. While the secretion of 3H-NA was not affected by known beta1-agonists, it was dose-dependently and reversibly increased by two different beta2-agonists. The effect of isoprenaline on 3H-NA secretion was not altered by a selective beta1-antagonist, but strongly reduced or abolished by a beta2-blocking drug. The results indicate that the beta-adrenoceptors involved in the control of NA secretion from the vasoconstrictor nerves of human omental blood vessels are only to a minimal extent stimulated by NA secreted from the nerves, and therefore do probably not mainly serve to mediate local positive feedback control of transmitter secretion; the receptors appear to be beta2 in nature.
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000328:Adult; D000368:Aged; D000420:Albuterol / Q000494:pharmacology; D001158:Arteries / Q000294:innervation; D004558:Electric Stimulation; D005260:Female; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D009638:Norepinephrine / Q000378:metabolism*; D009852:Omentum / Q000098:blood supply; D011217:Practolol / Q000494:pharmacology; D011412:Propanolamines / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D011941:Receptors, Adrenergic / Q000187:drug effects*; D012636:Secretory Rate / Q000187:drug effects; D013726:Terbutaline / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology; D014666:Vasomotor System / Q000502:physiology*; D014680:Veins / Q000294:innervation
D000319:Adrenergic beta-Antagonists; D011412:Propanolamines; D011941:Receptors, Adrenergic; D013844:Thiazoles; D011433:Propranolol; D007545:Isoproterenol; D013726:Terbutaline; D000420:Albuterol; D011217:Practolol; D009638:Norepinephrine