Endometrial blood flow in anaesthetized sheep as measured with krypton-85 clearance and microsphere techniques

Uterine blood flow rates were obtained with a Krypton (85Kr) clearance technique and with radio-active microspheres in six anaesthetized, non-pregnant ewes (a total of ten comparisons). 85Kr was administered, via a catheter, into the abdominal aorta and beta-emissions were detected with a catheter-type semi-conductor detector probe situated in the lumen of a uterine horn. In seven instances, the 85Kr clearance curve had only one component while in the remaining three instances the curves could be resolved into two components. The flow rates derived from the single component curves and the mean flow rates calculated from the curves with two components were of the same order as, and highly correlated with, estimates of capillary blood flow obtained with microspheres for either the caruncles, the inter-caruncular endometrium or the total endometrium (r = 0.832, r = 0.822 and r = 0.841, respectively, P less than 0.005). There was no correlation between the flow rates obtained with the 85Kr technique and estimates of myometrial capillary blood flow obtained with microspheres.