Angiotensin II (Ang II)‐pretreated female but not male rats are protected from pressor response and sympathetic activation to 2% saline drinking

Abstract

Growing evidence suggests sex differences in the development of hypertension. Previous work in our lab indicated male rats display a greater pressor response to 2% saline when sensitized with Ang II, so‐called “induced salt sensitivity”. In the current study, we hypothesized female rats are resistant to induced salt sensitivity. To test this hypothesis, blood pressure (BP) of female rats was monitored continuously with telemetry devices. Following an Induction‐Delay‐Expression (I‐D‐E) design, after one week recovery and one week baseline recording (B), rats received a subpressor dose of Ang II (10ng/kg/min, sc) via osmotic pumps for 7 days (I) and were then rested an additional 7 days to metabolize any exogenous Ang II (D). No difference in BP was detected during B, I, or D in these animals. During E, with 2% saline as the sole drinking fluid, no change in BP was detected in either control (97±2 mmHg, B, vs. 100±3 mmHg, E) or Ang II‐pretreated rats (99±2 mmHg, B, vs. 102±3 mmHg, E). To determine the influence of sympathetic tone on baseline BP, ganglionic blocker hexamethonium (30 mg/kg, ip) elicited similar reductions in BP in both control and pre‐treated Ang II female rats throughout the course of the study (B,I,D,E). These results suggest that female rats are protected from induced salt sensitivity, possibly through a resistance to sympathetic activation.