Enhanced insulin sensitivity in extrarenal potassium handling in uremic rats

Translocation of potassium to the intracellular compartment is impaired in advanced chronic renal failure. The purpose of this study was to evaluate the role of endogenous insulin in the disposal of an oral potassium load in uremia. Experiments were done on male Sprague-Dawley rats. Chronic renal failure (CRF) was induced by 3/4 nephrectomy. The results show that the addition of oral glucose to a potassium load was more effective in the translocation of potassium to the intracellular compartment in uremic animals. Further, suppression of endogenous insulin secretion with somatostatin caused a much higher increase in plasma potassium (K) of uremic rats (1.09 +/- 0.15 mEq/liter in CRF vs. 0.28 +/- 0.03 mEq/liter in control). Experiments to assess the activity of the Na pump were done in soleus muscles derived from these animals. Although a 50% reduction of the basal Na pump activity was found in the uremic muscles, the addition of insulin 100 mU/ml caused a relatively greater stimulation of ouabain-sensitive 86Rb uptake in the uremic muscle as compared to the control tissue (203% vs. 77% increment). These data suggest a greater sensitivity to insulin action on extrarenal potassium disposal in uremia.