Renin activity in the brain, the kidneys and the peripheral plasma or rats with different experimental models of hypertension.

Renin activity (RA) in peripheral plasma, as well as in renal cortex and brain (cortex, stem and medulla) homogenates of rats with spontaneous, Goldblatt, NaCl, adrenal-regeneration and neurogenic hypertension was biologically assayed. The results suggest that RA exists not only in the brain of normotensive but of hypertensive rats as well. RA in the medulla is higher than in other brain areas and in the kidney, both in normotensive and in hypertensive rats with the exception of rats with adrenal regeneration and NaCl hypertension. In most of the experimental forms of hypertension (neurogenic, renal, spontaneous) in which RA in the medulla is increased, the role of the brain renin-angiotensin system seems to predominate, while in forms in which renal RA is elevated (adrenal regeneration) the kidney renin system most probably plays a more important role. A definite inverse interrelation between the brain and the kidney renin-angiotensin systems was established. The interrelation between the two renin systems in NaCl hypertension could not be evaluated, since exogenous factors (Na), which interfere with the kidney renin system, play a considerable role in the pathogenesis of NaCl hypertension.