[Effects of indomethacin on renal and uterine blood flow and pressor responsiveness to angiotensin II or norepinephrine in pregnant dogs].
Pressor responsiveness to angiotensin II (A II) or norepinephrine (NE) in anesthetized nonpregnant and pregnant dogs, and the changes in renal blood flow (RBF) and uterine blood flow (UBF) elicited by the pressure rise in pregnant dogs were studied. Intervention of prostaglandins (PGs) in these hemodynamic responses was also examined, comparing the responses before and after the administration of indomethacin (IDM). The pressor responsiveness to the pressor substances was diminished in near term pregnant dogs in common with normal human pregnancy, and the refractoriness disappeared after the administration of IDM. RBF decreased following the infusion of A II or NE, and IDM enhanced the responses. A characteristic increase in UBF was observed following the infusion of A II exhibiting the maximum response at a dose of 0.05 microgram/kg, while it decreased following the infusion of NE, and these responses remained almost unchanged after IDM administration, although there was a 24.2% decrease in the base line value of UBF. It seems appropriate to conclude that PGs play a pivotal role in the development of the relative vascular refractoriness to infused pressor substances characterizing normal pregnancy, and also in preservation of RBF and UBF during pregnancy. Moreover, PGs attenuate the response of the renal vascular bed as well as systemic vascular bed to the pressor substances. However, the refractoriness of uterine vascular bed to A II remained almost unchanged regardless of PGs synthesis, suggesting the existence of another competitive factor involved in the effect of A II.
D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D001810:Blood Volume / Q000187:drug effects; D004285:Dogs; D005260:Female; D007213:Indomethacin / Q000494:pharmacology*; D009638:Norepinephrine / Q000494:pharmacology*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000187:drug effects*; D012079:Renal Circulation / Q000187:drug effects*; D014599:Uterus / Q000098:blood supply*
D000804:Angiotensin II; D009638:Norepinephrine; D007213:Indomethacin