[Studies on renal sympathetic nerve activity related to the existence of a utero-renal reflex in pregnant rabbit].

ABSTRACT

We have shown that the changes in renal blood flow (RBF) and renal sympathetic nerve activity (R-SNA) in metreurysis are different on the ovarian side from those on the cervical side. We examined their dissimilar mechanisms, and the changes in noradrenaline in the renal vein under metreurysis as an indicator of SNA and we also explored the pathway of Utero-Renal Reflex. In pregnant rabbits, SNA was measured by using bipolar electrode and renal cortical blood flow was measured by the thermocouple method. Noradrenaline was measured by HPLC. A small balloon was inserted into the uterine cavity on the ovarian or cervical side to increase the uterine resting tonus (URT). Noradrenaline increased under metreurysis with the increase in R-SNA. After protecting the abdominal large vessels an increase in URT in the cervical side caused the elevation of mean blood pressure, an increase in R-SNA and a decrease in RBF. After blocking the nerve around the suspensory ligaments an increase in URT in ovarian side did not cause an increase in R-SNA or a decrease in RBF. These data indicate that an increase in URT can stimulate R-SNA through the Utero-Renal Reflex, which in turn causes the deterioration of renal circulation.