Specific enhancement of norepinephrine-induced contraction in rat veins after beta adrenergic antagonists.
Propranolol markedly increased the norepinephrine-induced maximal force in circular smooth muscle of the rat portal, mesenteric, renal and, to a lesser extent, femoral veins without affecting aortic or mesenteric artery responses to norepinephrine. Furthermore, two other beta receptor antagonists, practolol and N-isopropylmethoxamine, specifically enhanced maximal venous responses to norepinephrine. Contractions to norepinephrine, but not to serotonin, were increased by propranolol only in veins, even after the vasodilator, papaverine. The ability of propranolol to enhance norepinephrine-induced contraction in these rat veins paralleled the effectiveness of isoproterenol to relax such tissues. In addition, beta receptor antagonists enhanced the response of veins to the field stimulated release of norepinephrine from sympathetic nerves. These data support the conclusion that beta adrenergic stimulation modulates norepinephrine-induced constriction in certain rat veins but not in the aorta or mesenteric artery.
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D004347:Drug Interactions; D004558:Electric Stimulation; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D008729:Methoxamine / Q000031:analogs & derivatives / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects*; D009126:Muscle Relaxation / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology*; D010208:Papaverine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D011217:Practolol / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D012701:Serotonin / Q000494:pharmacology; D014666:Vasomotor System / Q000187:drug effects*; D014680:Veins / Q000187:drug effects
D000319:Adrenergic beta-Antagonists; D012701:Serotonin; D011189:Potassium Chloride; D011433:Propranolol; D010208:Papaverine; D008729:Methoxamine; D007545:Isoproterenol; D011217:Practolol; D009638:Norepinephrine