The role of the renal sympathetic nerves in a model of postmenopausal hypertension

Abstract

The mechanisms responsible for the increase in blood pressure (BP) in postmenopausal women are unknown. Our preliminary studies suggest that the sympathetic nervous system may contribute to the hypertension (HT) in aging female SHR. The aim of this study was to determine whether the renal nerves contribute to HT in old and young female SHR. Female SHR (18 and 3 mos of age, respectively, n=4/grp) underwent uninephrectomy, and two weeks later, underwent unilateral renal denervation (O‐RD and Y‐RD) or sham surgery (O‐S and Y‐S) and telemetry transmitter implantation. After two weeks recovery, mean arterial pressure (MAP) and heart rate (HR) were recorded for 5 days. MAP was higher in O‐S than other groups (O‐S:167.5±2.4 vs O‐RD:138±2.7 mmHg; p<0.001; and Y‐S:140.6±6.3 vs Y‐RD:122.1±3.9 mmHg, p<0.001). The reduction in MAP after denervation was greater in O‐RD (O‐RD:29.5±0.5 mmHg, vs Y‐RD:17.0±0.9 mmHg, p<0.001). Renal NE content was significantly decreased compared to shams (O‐S: 201.1±30.3 pg/mg vs O‐RD: 35.6±10.3 pg/mg wet weight, p<0.001; and Y‐S:239±24.5 pg/mg vs Y‐RD:18.1±11.4 pg/mg wet weight, p<0.001). These data indicate that the renal nerves play a key role in the control of BP in pre‐ and post‐cycling SHR. The data also suggest that the renal nerves contribute to HT more in old females than young.