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 release. Effects of insulin (25 mU/ml) on basal (nonstimulated) immunoreactive (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 +/- 38.4 to 62.2 +/- 20.5 fmol/g/min). Insulin stimulated myocardial glucose utilization and lactate production approximately 2-fold, but uniformly decreased ir-ANF release by approximately 25%, regardless of age. Correlations between ir-ANF release and myocardial metabolism suggest independent influences of insulin on these two events. In addition, it appears that this model might be reasonably exploited to investigate episodic ANF release and its regulation during ontogeny and in a variety of physiological states.