Effects of ovarian hormones on ovarian capillary blood flow in anoestrous ewes.

The indicator fractionation technique with [86Rb]rubidium chloride as the indicator was used to determine the relative blood flow (RBF) as a measure of capillary blood flow in the ovaries of conscious, hormonally treated, anoestrous ewes. Treatment of ewes with either progesterone only or oestradiol only had no effect on ovarian RBF, but treatment with oestradiol subsequent to progesterone caused a significant increase (P less than 0.001). Consequently, it appears that progesterone-induced sensitivity of the ovarian vasculature to the vasodilatory effects of oestradiol may be responsible for increased ovarian blood flow around oestrus in cyclic ewes.