Developmental changes in the effect of acidosis on contraction, intracellular pH, and calcium in the rabbit mesenteric small artery
Developmental changes in the effect of acidosis on contraction, intracellular pH, and calcium in the rabbit mesenteric small artery
复制标题
DOI：
10.1203/00006450-199712000-00006
复制
发表时间：
1997-12-01
影响因子：
3.6
通讯作者：
Momma, K
中科院分区：
文献类型：
--
作者：
Nakanishi, T;Gu, H;Momma, K
本研究的目的是确定呼吸性酸中毒对血管平滑肌收缩影响的发育变化。在新生和成年兔肠系膜小动脉的插管标本中测量血管直径、细胞内 pH (pH(i)) 和钙浓度 ([Ca](i))。在高氯化钾预先收缩的动脉中，酸中毒会导致新生儿和成人的血管舒张。新生儿的血管舒张作用比成人更大。作为[Ca](i)指标的fura-2荧光比率在酸中毒期间短暂下降，并且两个年龄组的下降相似。在去甲肾上腺素预先收缩的动脉中，酸中毒导致成人短暂的血管收缩和新生儿的血管舒张。在这些血管中，fura-2 荧光比率在酸中毒期间短暂增加；两组的增幅相似。诱导酸中毒后，去甲肾上腺素或高 KCl 预收缩的动脉 pH(i) 迅速下降，且两组 pH(i) 的降低程度相似。在带皮平滑肌制剂中，成人中pH 7.1时的张力-[Ca]关系曲线与pH 6.8时的张力-[Ca]关系曲线没有显着差异。在新生儿中，与 pH 7.1 时相比，pH 6.8 时的张力-[Ca] 曲线向右移动。这些数据表明呼吸性酸中毒对早产儿血管的舒血管作用大于成人。新生儿更大的血管舒张不能用酸中毒期间 pH(i) 或 [Ca](i) 与年龄相关的差异来解释。新生儿肌原纤维对低 pH(i) 的敏感性较高，这可能至少在一定程度上是该年龄组血管舒张程度较高的原因。
The purpose of the present study was to determine developmental changes in the effect of respiratory acidosis on vascular smooth muscle contraction. Vessel diameter, intracellular pH (pH(i)), and calcium concentration ([Ca](i)) were measured in a cannulated preparation of the small mesenteric artery of newborn and adult rabbits. In the artery precontracted by high KCl, acidosis caused a vasorelaxation both in the newborn and the adult; the vasorelaxation was greater in the newborn than in the adult. The fura-2 fluorescence ratio, an indicator of [Ca](i), decreased transiently during acidosis and the decrease was similar in the two age groups. In the artery precontracted by norepinephrine, acidosis caused a transient vasoconstriction in the adult and a vasorelaxation in the newborn. In these vessels, the fura-2 fluorescence ratio increased transiently during acidosis; the increase was similar in the two groups. Upon induction of acidosis, pH(i) fell rapidly in the artery precontracted by norepinephrine or high KCl, and the depression of pH(i) was similar in the two groups. In the skinned smooth muscle preparation, a tension-[Ca] relationship curve at pH 7.1 was not significantly different from that at pH 6.8 in the adult. In the newborn, the tension-[Ca] curve at pH 6.8 was shifted to the right, compared with that at pH 7.1. These data suggest that the vasorelaxant effect of respiratory acidosis in the premature vessel is greater than in the adult. The greater vasorelaxation in the newborn cannot be explained by the age-related difference in pH(i) or [Ca](i) during acidosis. The greater sensitivity of myofibrils to low pH(i) in the newborn may, at least in part, be responsible for the greater vasorelaxation in this age group.