[Correlation between the perfusion, perfusion pressure and contractile activity in the nonpregnant uterus]

Abstract

This paper presents the results of investigations on the dependence between the flow and intravascular pressure and uterine contractile activity. The pressure in the vascular bed was monitored with a pressure transducer and the contractile activity by means of an intrauterine ballon was measured. In a part of experiments, the flow was recorded with a flowmeter. The investigations were performed on 27 nonpregnant human uteri in various phases of the menstrual cycle. Uterus was perfused with a perfusion pump, starting from the perfusion pressure of 50 to 60 mm Hg and on up to maximum values of 140 mm Hg. It has been found that with an increase in the uterine flow, intravascular pressure increases too. This pressure-flow relationship is linear. An increase in flow through the nonpregnant uterus leads to an increase in intravascular pressure from 61.5 mm Hg to 142 mm Hg with a simultaneous increase in the human uterine basal tonus from the 6.2 mm Hg initial value to the average value of 25 mm Hg at the perfusion pressure of 140 mm Hg and an decrease in frequency from 6.6 to 5.2 contractions/10 min. With an increase of flow, however, there is a increase in amplitude which reaches highest values at the 100 mm Hg perfusion pressure and than no significant increase in amplitude is observed. An increase in amplitude is accompanied by an increase in contractile activity. It should be concluded that hemodynamic conditions and the state of vessels play a controlling role in the process of the uterine activity.