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Infusion of KCI (0.25-3.0 mEq/kg/hr) into three intact dogs, four with bilateral ureteral ligation, and six animals with bilateral nephrectomy produced a rise 0 f peripheral plasma insulin levels and a gradual fall of plasma glucose concentrations. The percent fall of glucose levels was correlated (r = 0.83, P < .001) with the duration of the infusion. There was no change in the fasting hyperglycemia and barely detectable plasma insulin levels in three pancreatectomized dogs infused with KCI. FOUT dogs were sampled from their posterior superior duodenal veins. Three showed a marked rise in insulin levels within five minutes when the potassiulJl concentration was relatively unchanged and the other manifested late elevated central insulin levels when peripheral plasma values had returned to normal. These data suggest that changes in potassium concentration stimulate insulin secretion in vivo and the resultant inhibition of hepatic glucose production causes a progressive decline in systemic glucose concentration, The possibility of an insulin-potassium feedback system is discussed briefly.

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Dogs with ligated ureters were infused with KCI at rates that varied from 0.2 to 3 mEq/kg/hr, and infusion continued until the onset of cardiac manifestations of hyperkalemia, when serum potassium ranged between 9.9 and 11.0 mEq/L. It was found that ligated dogs were able to remove much of the infused potassium from extracellular fluid despite the suppression of urinary excretion. Pancreatectomized dogs lost the ability to remove infused potassium from extracellular fluid; treatment with insulin restored it completely. Addition of insulin (SU/kg/hr) to the infused KCI markedlyaugmented both tlte rate of potassium removal from extraceUular fluid and the arnount sequestered outside the extracellular compartment. In non-pancreatectomized liga ted dogs, the maximal rate of potassium removal without exogenous insulin was ~ 0.5 mEq/kg/hr, and maximal potassium sequestered 3.3 mEq/kg. Insulin added to the KCI infusion increased the rate to ~ 1.6 mEq/kg/hr and the arnount sequestered to -6.2 mEq/kg. Insulin may have an important physiological role in the regulation of serum potassium.

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