Pulmonary vasoactive effects of exogenous and endogenous AVP in conscious dogs.
Our objectives were to investigate the extent to which both exogenously administered and endogenously released arginine vasopressin (AVP) exert a direct, vasoactive influence on the pulmonary circulation of conscious dogs. Multipoint pulmonary vascular pressure-cardiac index (P/Q) plots were constructed during normoxia in conscious dogs by stepwise constriction of the thoracic inferior vena cava (IVC) to reduce Q. In intact dogs, AVP infusion (7.6 ng X kg-1 X min-1 iv) increased (P less than 0.01) plasma AVP from 2.3 +/- 0.4 to 280 +/- 23 pg/ml, and increased (P less than 0.01) the pulmonary vascular pressure gradient (pulmonary arterial pressure minus pulmonary capillary wedge pressure, PAP-PCWP) over the entire range of Q studied. Following administration of autonomic nervous system antagonists and a converting-enzyme inhibitor, exogenous AVP again increased (P less than 0.01) PAP-PCWP over the entire range of Q. Generation of P/Q plots via IVC constriction resulted in systemic hypotension (58 +/- 4 mmHg) and a concomitant increase (P less than 0.01) in endogenous AVP release from 2.1 +/- 0.2 to 109 +/- 22 pg/ml. Following administration of the specific AVP receptor antagonist [d(CH2)5]AVP (10 micrograms/kg iv), systemic arterial pressure, but not PAP - PCWP, was decreased to significantly lower levels as Q was reduced during IVC constriction. A similar response was observed in dogs pretreated with the neurohumoral blockers. Thus exogenous administration of AVP results in active, non-flow-dependent pulmonary vasoconstriction. This effect is not dependent on reflex activation of the autonomic nervous system or on the increased production of angiotensin II.(ABSTRACT TRUNCATED AT 250 WORDS)
D000806:Angiotensin-Converting Enzyme Inhibitors; D000818:Animals; D001127:Arginine Vasopressin / Q000037:antagonists & inhibitors / Q000494:pharmacology* / Q000502:physiology; D001794:Blood Pressure; D001808:Blood Vessels / Q000187:drug effects; D002302:Cardiac Output; D003243:Consciousness; D004285:Dogs; D008297:Male; D010276:Parasympatholytics / Q000494:pharmacology; D011652:Pulmonary Circulation / Q000187:drug effects*; D013565:Sympatholytics / Q000494:pharmacology; D014661:Vasoconstriction; D014682:Vena Cava, Inferior / Q000502:physiology
D000806:Angiotensin-Converting Enzyme Inhibitors; D010276:Parasympatholytics; D013565:Sympatholytics; D001127:Arginine Vasopressin