ラット胎仔動脈管におけるATP感受性カリウムチャンネル

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The O_2-sensing mechanism may be underdeveloped in the ductus arteriosus of the premature fetus. The ATP-sensitive K channel may be one of the O_2-sensors. This study was designed to investigate developmental changes in the ATP-sensitive K channel in smooth muscle cells of the ductus arteriosus in the rat fetus. The ductus arteriosus was isolated from fetal rats at 19 and 21 days of gestation (term; 21.5 days). The fetus at 19 days served as a model of the premature fetus. The effect of glybenclamide, an inhibitor of the ATP-sensitive K channel, on ductal contraction was studied. Glybenclamide caused significant contraction in the 21-days fetus, but not in the 19-day fetus. Whole-cell K currents were measured in single smooth muscle cells isolated from the ductus arteriosus using voltage-clamp techniques. The K current density activated by pinacidil, an opener of the ATP-sensitive K channel, and that inhibited by glybenclamide were significantly greater in the fetus at 21 days than in the fetus at 19 days of gestation. Glybenclamide depolarized the membrane potential in the two age groups, but the degree of depolarization in the 21-day fetus was significantly greater than in the 19-day fetus. These data suggest that K_<ATP> is underdeveloped in the premature fetus and support the hypothesis that K_<ATP> is one of the O_2 sensors in the DA and that O_2-induced contraction of the DA may not occur because K_<ATP> is underdeveloped in the premature fetus.
東京女子医科大学の論文
2002-12-25

ラット胎仔動脈管におけるATP感受性カリウムチャンネル

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