NEUROPEPTIDE-Y INFUSION DECREASES PLASMA-RENIN ACTIVITY IN POSTMYOCARDIAL INFARCTION RATS

We wished to determine if chronic neuropeptide Y (NPY) infusion (1 ng/ min for 1 week by Alzet minipump) could decrease plasma renin activity (PRA) and norepinephrine (NE) in a rat myocardial infarction (MI) mod el of moderate compensated congestive heart failure (CHF). CHF was pro duced by prior (6-8 weeks) ligation of the left coronary artery; contr ol rats were sham-operated. Carotid arterial blood was drawn for PRA a nd NE in conscious unrestrained rats that had been instrumented 24 h e arlier. MI rats had increased PRA as compared with sham-operated rats [8.73 +/- 1.27 vs. 5.10 +/- 0.91 ng angiotensin (AI) I/ml.h, mean +/- SE]. During chronic NPY infusion, PRA was reduced to normal in the MI group (4.78 +/- 0.91) but was not affected in the sham group (5.65 +/- 0.51). Plasma NE was altered similarly, but the changes did not reach statistical significance, These data suggest that NPY has the capacit y to restrain renin release in moderate compensated CHF.