Clearance and Metabolic Action of Insulin and Nonsuppressible Insulin-like Activity (NSILA) in the Isolated Perfused Rat Heart

Abstract

Several aspects of glucose-U-C-14 metabolism were studied in the isolated perfused rat heart to compare the activities of NSILA and crystalline insulin. Like insulin, porcine NSILA prepared on a Dowex-50 column caused significant glucose disappearance and glycogen deposition. While 50% of the insulin was cleared from the perfusate (immunoassay and bioassay) over 60 min. NSILA concentration, measured by the isolated fat cell bioassay, remained constant. These results establish myocardium as a tissue on which NSILA has an action similar to insulin. Furthermore, these studies show an action of NSILA via a "normal" vascular tree and support the possibility that it may have a physiologic role. The lack of clearance of NSILA suggests that it may exert its insulin-like action over long intervals.