Anteroventral third ventricle and renin-angiotensin system interaction in the two-kidney, one clip hypertensive rat

To test the peripheral mechanisms of prevention and reversal of two-kidney, one clip (2K1C) hypertension in the rat by lesion of the anteroventral third ventricle (AV3V) region, we studied blood pressure responses in rats to AV3V lesion produced before (n = 8) or after (n = 8) clipping the left renal artery. Two groups of sham-lesioned, clipped rats (n = 9 each) served as controls. At the end of the experiments, saralasin and captopril were given to evaluate the angiotensin-dependent component of blood pressure. To study the influence of the procedures on plasma renin activity (PRA), two parallel groups of rats (n = 26 and 24, respectively) were submitted to similar surgical protocols. We observed that increases in blood pressure were significantly smaller in the previously lesioned compared to previously sham-lesioned animals (delta BP = 21.5 +/- 3.7 vs. 32.9 +/- 2.5 mm Hg, p less than 0.01); also, AV3V lesion almost completely reversed hypertension (BP from 167.5 +/- 2.9 to 136.0 +/- 4.1 mm Hg, p less than 0.001), which was not observed in the sham-lesioned animals (BP from 172.0 +/- 2.8 to 168 +/- 2.7 mm Hg, NS). Saralasin produced a significantly smaller decrease in BP in the lesioned animals compared to those with sham lesions during both prevention and reversal experiments. Similar results were observed with captopril. Previous AV3V lesion did not significantly affect PRA with clipping of the renal artery, but AV3V destruction after hypertension had been established resulted in significantly lower PRA compared to sham-lesioned animals (4.58 +/- 0.72 vs 8.38 +/- 1.79, respectively, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)