[Brain and kidney renin-angiotensin system in rats with simultaneously induced cerebral and renal ischemia]

The objective of the present work was to study the changes in the brain and renal renin-angiotensin system (RAS) during their simultaneous stimulation by ischemia. Experiments were carried out on the following groups of male normotensive Wistar rats: intact, with brain ischemia, with renal ischemia, with combined brain and renal ischemia. The three ischemic groups of animals had some arterial pressure elevation without reaching hypertensive values. In animals with combined brain and renal ischemia brain renin concentration (BRC) was raised, while plasma renin activity (PRA) was reduced relative to the intact controls, i.e. as in animals with brain ischemia alone. Renal renin concentration (RRC) in the ischemic kidney was at the level of the one in intact animals and in animals with brain ischemia. In the intact contralateral kidney of rats with combined ischemia RRC was reduced relative to the intact kidney of animals with renal ischemia and statistically insignificantly reduced relative to the RRC in intact controls and in animals with brain ischemia. The results of this study showed that inverse ratio between renal and brain RAS exists also in the single clamped--birenal model of hypertension. Interaction between the two RAS is manifested when they both are simultaneously stimulated, with prevalence of the effect of brain RAS, which affects renin secretion in the kidney.