Renin substrate, active and acid-activatable renin concentrations in human plasma and endometrium during the normal...

Renin substrate, active and total renin concentrations were measured in plasma and endometrial samples obtained from 101 patients, all of whom were having normal menstrual cycles. The endometrial samples were found to contain all of these components of the renin-angiotensin system in considerably higher concentrations than those found in the plasma. There was no correlation between the plasma and endometrial concentrations of any of these substances and it is suggested that they may be produced locally in the endometrium. A marked increase in the angiotensin producing potential of the endometrium was noted immediately before menstruation, indicating a possible function in the control of endometrial blood flow.