The effects of age, nitric oxide synthase inhibition with L-NAME and combined nitric oxide synthase and cyclooxygenase inhibition (L-NAME & Indo) on vasodilator responses of the PNA to increasing doses of the endothelium-dependent vasodilator acetylcholine.

<p>The PNA responses are determined in young and old A) intact, B) ovariectomized (OVX), and C) ovariectomized and estrogen replaced (OVX+E2) female rats. A. There was an age-related difference in vasodilator responses between young and old INTACT female rats. Blockade with L-NAME significantly reduced vasodilation in both groups (<i>P</i><0.05) and abolished the age-related difference in the vasodilator response. The combined blockade with L-NAME and Indo further reduced PNA vasodilation in the young rats (<i>P</i><0.05). B. There were no differences in the vasodilator response between young and old OVX rats under any of the three conditions. Blockade with L-NAME significantly reduced vasodilation in both groups (<i>P</i><0.05), and the combined blockade further diminished vasodilation in both OVX groups (<i>P</i><0.05). C. There were no differences in vasodilator responses between young and old OVX+E2 rats under any of the three conditions. Inhibition with L-NAME significantly reduced vasodilation in both groups (<i>P</i><0.05), whereas the combined L-NAME & Indo blockade had no further effect than L-NAME alone. Values are means ± S.E; <i>n</i> = 9–11 animals per group. *Indicates the vasodilator response is significantly different between groups (<i>P</i><0.05).