Hemodynamic responses to acute angiotensin II infusion are exacerbated in male versus female spontaneously hypertensive rats

We previously reported that male spontaneously hypertensive rats ( SHR s) are more sensitive to chronic angiotensin (Ang) II ‐induced hypertension compared with female rats. This study was designed to test the hypothesis that anesthetized male SHR s are also more responsive to acute Ang II ‐induced increases in blood pressure and renal hemodynamic changes when compared with female SHR s. Baseline mean arterial pressure ( MAP ) was higher in male SHR s than in female SHR s (135 ± 2 vs. 124 ± 4 mmHg, P  < 0.05). Acute intravenous infusion of Ang II (5 ng/kg/min) for 60 minutes significantly increased MAP to 148 ± 2 mmHg in male SHR s ( P  < 0.05) without a significant change in MAP in female SHR s. Baseline glomerular filtration rate ( GFR ) was also higher in male SHR s than in female SHR s (2.6 ± 0.3 vs. 1.3 ± 0.1 mL/min, P  < 0.05). Ang II infusion for 60 min significantly decreased GFR in male SHR s (2.0 ± 0.2 mL/min; P  < 0.05) without significant changes in urine flow rate, sodium, or chloride excretion. In contrast, Ang II infusion increased GFR in female SHR s (1.9 ± 0.2 mL/min; P  < 0.05). The increase in GFR upon Ang II infusion in female SHR s was associated with increases in urine flow rate (4.3 ± 0.3 to 7.1 ± 0.9  μ L/min), sodium excretion (0.16 ± 0.04 to 0.4 ± 0.1  μ mol/min), and chloride excretion (0.7 ± 0.08 to 1.1 ± 0.1  μ mol/min; for all P  < 0.05). These findings support the hypothesis that there is sex difference in response to acute Ang II infusion in SHR s with females being less responsive to Ang II ‐induced elevations in blood pressure and decreases in GFR relative to male SHR s.