Effect of icv AT1 receptor antisense ODN on the baroreflex control of renal sympathetic nerve activity (RSNA) in conscious Wistar and spontaneously hypertensive rat (SHR)

Abstract

This study determined the impact of AT1 receptor antisense ODN given icv on the baroreflex control of RSNA in conscious rats. Male Wistar and SHR (n=5–6) were chronically instrumented with cannulae in the femoral artery and jugular vein, electrodes sealed onto the left renal nerve and a cannula implanted into the right lateral cerebroventricle. Three days later, blood pressure (BP) was manipulated by iv phenylephrine and nitroprusside (both at 10μg) to generate baroreflex curves for RSNA (Huang et al 2006, J Physiol 574: 597–604) before and 1 day after the icv administration of 25μg AT1 receptor antisense ODN or 25μg sense ODN dissolved in 20μl lipofectin (1 μg/μl). Means ±SEM were subjected to Student’s t test and significance taken at P<0.05. In Wistar rats, BP was 115±5mmHg and was unchanged after the AT1 receptor antisense ODN, but there was a significant (P<0.05) increase in the sensitivity of the baroreflex curve of 86.0%. BP in the SHR, at 172±5mmHg, was decreased after the antisense ODN to 148±6mmHg (P<0.05), while the sensitivity of the baroreflex curve increased by 55.1% (P<0.05). Administration of the sense ODN had no effect on BP or the baroreflex curves in either Wistar or SHR. The data showed that whereas the AT1 receptor antisense ODN decreased BP only in the SHR, it increased the sensitivity of the baroreflex control of RSNA in both conscious Wistar and SHR.