EFFECTS OF ACUTE RUNNING EXERCISE ON WHOLE-BODY INSULIN ACTION IN OBESE MALE SHHF MCC-FA(CP) RATS

This study utilized the obese male spontaneously hypertensive heart failure rat (SHHF/Mcc-fa(cp)), which has metabolic features very similar to human non-insulin-dependent diabetes mellitus. The purpose of this study was to assess the insulin sensitivity and responsiveness of whole body glucose disposal and insulin suppressability of hepatic glucose production with use of the euglycemic-hyperinsulinemic clamp procedure in 12- to 15-wk-old SHHF/Mcc-fa(cp) rats at rest (OS) and 2.5 h after a single session of acute exercise (OE). Lean male SHHF/Mcc-fa(cp) rats were sedentary (LS) control animals. At least three clamps producing different insulin-stimulated responses were performed on each animal in a randomized order. At this age the obese animals are normotensive and have not developed congestive heart failure. Compared with LS, OS were significantly hyperglycemic and hyperinsulinemic and insulin sensitivity and responsiveness of whole body glucose uptake and insulin suppressability of hepatic glucose production were significantly decreased. Compared with LS and OS, acute exercise significantly decreased resting plasma glucose but did not alter plasma insulin. Compared with OS, acute exercise significantly increased the insulin responsiveness of whole body glucose disposal but did not affect the sensitivity of whole body glucose disposal or insulin suppressability of hepatic glucose production. Compared with LS, however, acute exercise did not ''normalize'' the insulin responsiveness of whole body glucose disposal. Thus a single acute exercise session improves but does not normalize whole body insulin resistance in the SHHF/Mcc-fa(cp) rat.