Effects of indomethacin, during pregnancy in the rat, on responses to noradrenaline and angiotensin II in vivo, and responses to phenylephrine in vitro

Abstract

Pressor responses to both angiotensin II (Ang II) and noradrenaline (NA) were reduced in 20-day-pregnant rats compared with those in non-pregnant animals, regardless of whether the results were expressed in terms of the dose per kilogram of body weight or per millilitre of estimated plasma volume. Inhibition of prostaglandin production with indomethacin (10 mg kg-1, i.v.) was not accompanied by any significant effect on responses to Ang II in either non-pregnant or 20-day-pregnant animals. However, it attenuated the effects of NA in 20-day-pregnant rats. Indomethacin (10(-5) or 3 x 10(-5) M) did not potentiate in vitro vasoconstrictor responses to phenylephrine of endothelium-intact or -denuded thoracic aortic rings from non-pregnant or 20-day-pregnant rats. These results suggest that subsensitivity to Ang II or NA during pregnancy in the rat is not due to dilution of the dose of these autacoids resulting from increased plasma volume, nor to an increased output of vasodilator prostaglandins.