Figure 1.
Rapid activation of eNOS in endothelial cells. (a) Effect of E2 on eNOS activity in intact PAEC. [3H]l-arginine conversion to [3H]l-citrulline was measured over 5–15 min in the presence of 10–8 M E2. (b) Effect of actinomycin D (Act D) on the rapid activation of eNOS. After 120 min preincubation in the absence or presence of 25 μg/ml Act D, 15 min incubations were done with or without continued Act D and either 10–8 M E2 or the calcium ionophore A23187 (10–5 M). (c) Effect of tamoxifen on E2-stimulated eNOS activity. Fifteen-minute incubations were performed in the absence or presence of 10–8 M E2, with or without 10–6 M tamoxifen (Tam) added simultaneously. Partial inhibition (50%–70%) was also noted with 10–8 M Tam (13). (d) Effect of ICI 182,780 on E2-stimulated eNOS activity. Fifteen-minute incubations were performed in the absence or presence of 10–8 M E2, with or without 10–5 M ICI 182,780 added simultaneously. Full inhibition was also observed with 10–6 M ICI 182,780 (13). Values are mean ± SEM; n = 4–6. *P < 0.05 vs. basal. E2, estradiol-17β; eNOS, endothelial nitric oxide; PAEC, pulmonary artery endothelial cells.