Fig. 7.

Concentration-response curves to Dea-NONOate, an exogenous NO donor. Vasodilation to Dea-NONOate did not change with advancing age (A). Ovariectomy and ovariectomy with estrogen replacement did not alter vasodilator responses to Dea-NONOate in arterioles from young (B) or old (D) rats. Sensitivity (IC₅₀) in coronary arterioles from middle-aged OVE was greater than those from middle-aged OVX (middle-age OVX: 2.31×10⁻⁶ M, Middle-age OVE 7.01×10⁻⁷ M) (C). Values are expressed as means ± SE. §Significant OVE effect vs. age-matched OVX (P ≤ 0.05).