Plasma enzymes in relation to aldosterone administration and heat acclimatization in rats.

Abstract

Acclimatization of mammals to a hot environment is accompanied by an increased output of aldosterone and enhanced activity of several blood enzymes, yet the role of aldosterone in activation of the blood enzymes has not been fully elucidated. In this investigation the activity of several plasma enzymes was studied in groups of rats treated separately with 2 [mu]g D-aldosterone monoacetate/g body weight, 0.6 [mu]g adrenaline [epinephrine]/g body weight, exposure to heat stress, or acclimatization to a hot environment without physical activity. A single injection of aldosterone produced a rise in the level of glutamic oxalacetic transaminase (GOT), (P< 0.05) and glutamic pyruvic transaminase (GPT) (P < 0.01) with insignificant changes in lactic dehydrogenase (LDH). While the enzymic responses in rats exposed to heat stress were lower than those observed in animals treated with a single aldosterone injection, a single epinephrine administration elevated (P < 0.01) the values of GOT, GPT, and LDH. Prolonged administration of aldosterone elicited a marked rise in GOT and only a slight one in LDH which was similar to the value of GOT (P < 0.05), GPT (P< 0.01), and LDH observed in heat-acclimatized animals. Electrophoretic studies revealed that chronic aldosterone treatment and heat acclimatization did not produce abnormal plasma LDH isoenzyme pattern.