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.