Kaluresis and Cardiac Sensitivity to Hyperkalaemia in Intact and Adrenalectomized Rabbits 1

Abstract

Summary

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 prein-fusion 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 ~10.2 meq/liter, i.e., 5.6 meq/liter above the mean of the prein-fusion 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 ~7.6 meq/liter—about 2.9 meq/liter above the preinfusion value.

We thank Alexander Miller, Stephen Oppenheim, and Roger Cutting. Their uncanny skill with rabbits made their technical assistance indispensable.