Inhibitive effect of hypoxia on vasoconstriction of phenylephrine in mesenteric arterioles of guinea pig / 实用医学杂志

ABSTRACT

Objective To investigate the effects and mechanisms of hypoxia on the contraction of mesen-teric arteries induced by phenylephrine (PE) in guinea pig. Methods Pressure myograph system was used to study the effects of 20, 40 and 60 min hypoxia (mixed with 95% CO2 and 5% O2) on the constriction induced by PE in acutely separated mesenteric artery (300 ~ 400 μm) of guinea pig. Results PE (0.1 ~ 100 μmol/L) caused the contractions of the mesenteric arteries in guinea pig in a concentration-dependent way . Hypoxia de creased the pH value of perfusion fluid from 7.4 to 6.3. Hypoxia significantly inhibited PE-induced vasocon-striction, and the inhibition was hard to recover after reoxygenation. Hypoxia inhibited PE-induced vasoconstric-tion in a time-dependent way , with the inhibition rate reduced in the sequence of inhibition duration of 60 , 40 and 20 min. When its value was decreased to 6.3 , the perfusion fluid even inhibited PE-induced vasoconstric tion. Conclusion Hypoxia can inhibit PE-induced vasoconstriction in the mesenteric arteries of guinea pig in a time-dependent way. The mechanism may have something to do with the change of pH.