Kaluresis and cardiac sensitivity to hyperkalaemia in intact and adrenalectomized rabbits

Rabbits K loaded by infusion of 2 meq KCl/kg/hr excrete over 55% of the administered K in the urine and do not develop prelethal ECG changes until mean serum K attains to 14.9 meq/liter, i.e., 11.8 meq/liter above the average preinfusion level. Four hours after bilateral adrenalectomy there is a profound diminution of urinary K loss in K loaded rabbits--less than 7% of the infused K is excreted. There is, however, no significant change in cardiac sensitivity to hyperkalemia. K loaded dogs lose only about 20% of infused K in the urine and develop prelethal ECG changes at similar to 10.2 meq/liter, i.e., 5.6meq/liter above the mean of the preinfusion levels. After adrenalectomy, urinary K loss is only moderately diminished (12% of infused K is still found in the urine), but cardiac sensitivity to K is markedly increased: prelethal ECG changes appear at a serum K level of similar to 7.6 meq/liter--about 2.9 meg/liter above the preinfusion value.