Plasma renin activity in hyperthermic rats

Heating rats exposed 30' to a 40 degrees C environmental temperature increases plasma renin activity (PRA). Propranolol as such decreased PRA, but heating propranolol-treated rats induced also an increased PRA. Hexamethonium increases PRA, that increases additionally when rats are heated. It may be concluded that increased PRA by heating is produced by other ways as catecholamine response and stimulation of beta-receptors, despite the important sympatho-adrenergic reaction that occurred in this circumstance [6], [13], probably by a decreased glomerular filtration rate and consequently that of Na in macula densa. Hyperthermia produced also an important plasma aldosterone increased concentration.