FIG. 3.

Bradykinin (BK)-induced tone of the rat intramural coronary arterioles was expressed as active strain and a function of intraluminal pressure (10⁻⁶ M BK). Values from the control angiotensin II-treated group (AII; full circles, n = 11), ovariectomy (OVX; empty circles, n = 11), and estrogen-treated (full triangles, n = 11) groups are shown. Mean ± SEM values. Asterisk indicates statistical significance (P < 0.05) between estrogen-treated group versus OVX group in respect of BK-induced tone (A) and control AII and estrogen-treated groups versus OVX group in respect of BK relaxation (B). Remaining tone was significantly higher in the estrogen-treated and control AII hypertensive group compared with the ovariectomized animals in BK-induced relaxation. Comparing with spontaneous tone, there was no significant relaxation in the ovariectomized group; however, estradiol treatment restored nitric oxide-dependent, BK-induced relaxation to the hypertensive control level.