Humoral regulation of vascular resistance after 30 days of pulmonary artery constriction.
In an earlier study of guinea pigs with constriction of the pulmonary artery (PA) for 30 days, hindquarters' vascular resistance was maintained primarily by humoral mechanisms. In the present study, we investigated the contribution of circulating catecholamines, angiotensin II, and other constrictor stimuli to hindquarters' vascular resistance by observing vasodilator responses to specific competitive antagonists. Pressure-flow curves indicated vascular resistances in isolated, perfused, sympathectomized hindquarters of anesthetized guinea pigs. Phentolamine produced significantly greater (P less than 0.05) vasodilatation in animals with constriction of pulmonary artery than in sham animals [Sar1-Ala8]angiotensin II produced no vasodilation in either group. After alpha-adrenergic blockade, papaverine produced similar vasodilatation and similar final perfusion pressures in both groups. It appears that circulating catecholamines and augmented vasoconstrictor responsiveness to norepinephrine are totally responsible for the increased humoral regulation of vascular resistance in this experimental model of right ventricular hypertrophy.
D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D006332:Cardiomegaly / Q000503:physiopathology*; D002395:Catecholamines / Q000494:pharmacology*; D004298:Dopamine / Q000097:blood; D004837:Epinephrine / Q000097:blood; D006168:Guinea Pigs; D006333:Heart Failure / Q000503:physiopathology*; D009638:Norepinephrine / Q000097:blood; D010208:Papaverine / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D012504:Saralasin / Q000494:pharmacology; D013564:Sympathetic Nervous System / Q000503:physiopathology; D014446:Tyrosine 3-Monooxygenase / Q000097:blood; D014655:Vascular Resistance
D002395:Catecholamines; D000804:Angiotensin II; D010656:Phenylephrine; D010208:Papaverine; D014446:Tyrosine 3-Monooxygenase; D012504:Saralasin; D004298:Dopamine; D009638:Norepinephrine; D004837:Epinephrine; D010646:Phentolamine