INSULIN REDUCES BASAL RELEASE OF ATRIAL-NATRIURETIC-FACTOR BY ISOLATED, PERFUSED NEONATAL PIG HEARTS

Plasma atrial natriuretic factor (ANF) levels are markedly altered in diabetic rodents suggesting that insulin might be a modulator of ANF r elease. Effects of insulin (25 mU/ml) on basal (nonstimulated) immunor eactive (ir)-ANF release by isolated neonatal pig hearts paced at 150 beats/min and perfused with no change in atrial stretch were examined. Release of ir-ANF decreased with age from 1-3 days postpartum (146.0 +/- 3 8.4 to 62.2 +/- 20.5 fmol/g/min). Insulin stimulated myocardial glucose utilization and lactate production approximately 2-fold, but u niformly decreased ir-ANF release by approximately 25%, regardless of age. Correlations between ir-ANF release and myocardial metabolism sug gest independent influences of insulin on these two events. In additio n, it appears that this model might be reasonably exploited to investi gate episodic ANF release and its regulation during ontogeny and in a variety of physiological states.