Responses of pulmonary vasculature of cattle to dopamine and apomorphine.
Both dopamine and apomorphine caused concentration-dependent contractions of the bovine pulmonary artery from rest. Both of these compounds caused of the bovine pulmonary artery from rest. Both of these compounds caused relaxation of histamine-precontracted arterial and venous strips after alpha-adrenoceptor blockade. Arterial contraction elicited by dopamine was inhibited either by phentolamine (alpha-blocker) or by the dopamine-selective antagonists, spiperone and butaclamol. Apomorphine in the highest concentration (greater than 10(-5) M) inhibited dopamine-induced contractions. Dopamine- and apomorphine-induced vascular relaxations were attenuated by propranolol but not by spiperone or butaclamol. These data suggest that dopamine- and apomorphine-induced relaxation in these preparations is most likely mediated through beta-adrenergic mechanisms, whereas dopamine-induced contractions seem to involve both alpha-adrenergic and dopaminergic receptors.
D000818:Animals; D001058:Apomorphine / Q000494:pharmacology*; D002417:Cattle / Q000502:physiology*; D004298:Dopamine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D011433:Propranolol / Q000494:pharmacology; D011651:Pulmonary Artery / Q000187:drug effects* / Q000502:physiology; D011954:Receptors, Dopamine / Q000187:drug effects; D013134:Spiperone / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects
D011954:Receptors, Dopamine; D013134:Spiperone; D011433:Propranolol; D001058:Apomorphine; D004298:Dopamine