Effect of chronic hypoxia on adrenoceptor responses of ovine foetal umbilical vessels

摘要

The effects of chronic hypoxia on α_1-adrenoceptor-mediated contractions were investigated in foetal umbilical vessels obtained from near-term(～140 day gestation)pregnant sheep maintained near sea level(～300 m) and at high altitude(3820 m) from 30 day gestation. Chronic hypoxia significantly decrease contractile sensitivity of the umbilical vein to noradrenaline (pD_2: 6.22±0.19 vs 5.67±0.9) and reduced the maximum response by 43/100. Noradrenaline-induced contraction of the umbilical artery was abolished. In contrast, contractions to KCl were not affected by chronic hypoxia.