Effect of Adrenalectomy, Desoxycorticosterone and Cortisone on Brain Potassium Exchange

Abstract

Thirty-four adrenalectomized rats were maintained on saline soln. for 5-7 days postoperatively and then injd. intraperit. with radioactive K. The animals were decapitated 4, 16, 39, or 54 hrs. later, and plasma and brain activity and total K were measured. The effects of saline soln., DOCA, and cortisone were studied in a similar manner at 4, 16, and 39 hrs. Adrenalectomy does not appreciably change the influx K into rat brain. However, the ratio of influx to outflux indicates that all brain K is exchangeable. In contrast, normal animals have a nonexchanging compartment amounting to 20 m.eq/kg. brain. Cortisone in adrenalectomized animals restores the nonexchangeable compartment; DOCA and saline soln. do not. Despite varying plasma K levels, the K influx into brain is approx. the same, suggesting that the K. system for brain is a carrier-limited one.