ADAPTATION TO SODIUM RESTRICTION IN RENIN-IMMUNIZED SPONTANEOUSLY HYPERTENSIVE AND NORMOTENSIVE RATS

The influence of active immunization against renin on the systemic and renal adaptation to abrupt suppression of dietary sodium was assessed in spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats. Very low level of plasma renin activity and no response of circulating renin to sodium restriction were observed in immunized rats. The final systolic arterial pressure achieved in immunized SHR (144 +/- 3 mmHg) was similar to that observed in nonimmunized WKY (137 +/- 4 mmHg), and no influence of renin immunization on renal blood flow was observed in both strains maintained on ad libitum sodium intake. Dietary sodium restriction was associated with a consistent decrease in arterial pressure in immunized rats, whereas no change occurred in sham-immunized rats. No impairment in the renal adaptation was detected in immunized rats (6-day cumulative sodium excretion of 1.67 +/- 0.2 and 1.65 +/- 0.3 mmol in immunized SHR and WKY, respectively, and 1.50 +/- 0.2 and 1.21 +/- 0.2 mmol in sham-immunized SHR and WKY rats). These studies indicate that renin immunization decreases arterial pressure but does not affect renal adaptation to dietary sodium restriction in hypertensive and normotensive rats.