Catecholamine-mediated pressor responses to angiotensin II in the Pekin duck, Anas platyrhynchos.
Asp1,Val5-angiotensin II (AII) caused dose-dependent increases in aortic blood pressure (BP) when injected into anesthetized Pekin ducks. Norepinephrine (NE) and epinephrine (E) concentrations in arterial plasma were found to be elevated 1 min after injection of AII, when BP was peaking, while plasma levels of unconjugated dopamine (DA) did not undergo any consistent change. Pretreatment with 6-hydroxydopamine (6-OHDA) rendered ducks supersensitive to the pressor effect of injections of NE, but did not affect adrenal chromaffin cell granulation, plasma NE and E concentrations, or pressor responses to tyramine and AII. Depletion of endogenous NE and E stores, following treatment with reserpine, did not affect pressor responses to NE, but diminished pressor responses to tyramine and AII. The discrepancies in the responses of 6-OHDA-treated ducks and reserpinized ducks to exogenous NE and AII indicate different pressor mechanisms for the two hormones. It is suggested that mobilization of endogenous NE and E contributes to the rise in BP observed following AII injection.
D000804:Angiotensin II / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002395:Catecholamines / Q000502:physiology*; D004372:Ducks / Q000502:physiology*; D004837:Epinephrine / Q000097:blood; D006892:Hydroxydopamines / Q000494:pharmacology; D008297:Male; D009638:Norepinephrine / Q000097:blood / Q000494:pharmacology; D016627:Oxidopamine; D012110:Reserpine / Q000494:pharmacology
D002395:Catecholamines; D006892:Hydroxydopamines; D000804:Angiotensin II; C031193:angiotensin II, Asp(1)-Val(5)-; D012110:Reserpine; D016627:Oxidopamine; D009638:Norepinephrine; D004837:Epinephrine