Female Spontaneously Hypertensive Rats (SHR) have greater increases in NOS in mesenteric arteries than males

Abstract

Female SHR have greater levels of Ang (1–7) and greater NO production than male SHR. This study tested the hypothesis that infusion of Ang (1–7) increases NO synthase (NOS) activity and expression more effectively in female SHR than in males. 11 week old male and female SHR received minipumps to deliver Ang (1–7) (24 μg/kg/hr; n=3–13). After 2 week, the renal cortex and mesenteric arteries were isolated to assess total NOS activity, NOS1 and NOS3 protein expression. NOS activity and protein expression were similar in the renal cortex of untreated male and female SHR and Ang (1–7) infusion did not alter NOS activity or protein expression in either sex. Similarly, NOS activity and protein expression were comparable in mesenteric arteries from untreated female and male SHR. Ang (1–7) infusion increased NOS activity in mesenteric arteries from female (47±5 to 82±12 pmol/mg, p≤.01) and male SHR (38±3 to 50±6 pmol/mg, p≤.05); however the increase in NOS activity was greater in females. Increased NOS activity was not associated with changes in NOS1 protein expression in either sex, however, Ang (1–7) increased NOS3 (endothelial NOS) protein expression in females (0.6±0.05 to 0.8±0.08 densitometric units, p≤.01), with no effect in male SHR. In conclusion, female SHR more sensitive to tissue specific Ang (1–7) mediated increases in NOS activity and expression, which may contribute to lower blood pressure in female SHR.