[Experimental study of renal and uterine blood flow regulation in obstetric hypovolemic shock (author's transl)]

Dynamics of the renal and uterine circulation in response to the hypovolemic shock were studied in anesthetized pregnant and nonpregnant dogs. The renal arterial blood flow (RABF), uterine arterial blood flow (UABF) and mean arterial blood pressure (MAP) were electronically integrated and recorded during the removal of 500 ml blood at the rate of 3 ml per minute. In nonpregnant bitches, there was a pronounced decrease in RABF after the 300 ml blood removal, and it became 85.2 per cent from the control level at the time of 500 ml blood removal (MAP 34.6 mmHg). In pregnant bitches however, the rapid decrease in UABF was invoked after the 200 ml blood removal, reaching 85.3 per cent decrease from the control level at the time of 500 ml blood removal (MAP 59.8 mmHg), while the decrease in RBF was attenuated in comparison with the nonpregnant animals. The decrease in UBF in pregnant animal was associated with remarkable increase in uterine vascular resistance. This implies that the hypovolemic shock generates a lending and borrowing phenomenon between the renal and uterine circulation in pregnant subject. As evidenced by the enhanced vasoconstrive responses of uterine vascular bed to injected norepinephrine (50 microgram) during the hypovolemic shock in pregnant animals, the activation on alpha receptors in the uterine vascular bed is the main cause of the phenomenon.