Potentiating effects of angiotensin II on norepinephrine-induced vasoconstriction in isolated and perfused dog mesenteric arteries.
Effects of angiotensin II on norepinephrine- and KCl-induced vasoconstrictions were investigated in isolated canine mesenteric arteries which were perfused with Krebs' solution at 37 degrees C. Angiotensin Ii at 0.03-0.3 microgram showed tachyphylaxis in the injection intervals used (10, 20 or 30 min intervals). After treatment with angiotensin II (0.18-1.8 microgram), norepinephrine- and KCl-induced constrictions were consistently potentiated. Imipramine which blocked tyramine-induced action did not significantly influence norepinephrine-induced constriction. pretreatments with both angiotensin II and indomethacin enhanced norepinephrine-induced constriction much greater than that with angiotensin II alone. It is suggested that angiotensin II may modify intracellular Ca movements and prostaglandin production induced by norepinephrine.
D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D004285:Dogs; D004357:Drug Synergism; D006339:Heart Rate / Q000187:drug effects; D066298:In Vitro Techniques; D008638:Mesenteric Arteries / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology*; D011189:Potassium Chloride / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects*
D000804:Angiotensin II; D011189:Potassium Chloride; D009638:Norepinephrine