Effects of atrial natriuretic peptide and nitroprusside on isolated pulmonary resistance and conduit arteries from rats with pulmonary hypertension.

摘要

1. The relaxant effects of atrial natriuretic peptide (ANP) and nitroprusside were studied on prostaglandin F2 alpha (PGF2 alpha)-contracted preparations of pulmonary resistance vessels (internal diameter 200-500 microns) and main pulmonary arteries taken from rats with pulmonary hypertension induced by monocrotaline (105 mg kg-1, s.c., 4 weeks previously). Control rats received saline. 2. In preparations from monocrotaline-treated rats, the potencies (negative log EC50) of ANP on resistance vessels (8.45) and main pulmonary arteries (8.25) were similar to those obtained in vessels from control rats (8.78 and 8.53 respectively), whereas those of nitroprusside were significantly less than in controls in both resistance vessels (7.13 compared with 7.63 in controls; three fold decrease in potency) and main pulmonary arteries (6.92 compared with 8.17 in controls; 18 fold decrease in potency). 3. On pulmonary resistance vessels from monocrotaline-treated rats, the maximum relaxant responses to ANP and nitroprusside, and also to pinacidil, were increased compared with controls, and reversal of the PGF2 alpha-induced contraction by these drugs was greater than 100%. In contrast, on main pulmonary arteries from monocrotaline-treated rats, the maximum relaxations to ANP and nitroprusside were not increased relative to controls, and reversal of PGF2 alpha was not greater than 100%.(ABSTRACT TRUNCATED AT 250 WORDS)