Research on the effect of acidosis on the vascular function in the premature vessels

本研究探讨了呼吸性酸中毒对新生和成年兔主动脉和肠系膜动脉细胞内pH （pH_i）、细胞内钙浓度（[Ca] _i）和血管收缩的影响。在分离环制备过程中测量了等长张力。用50mM氯化钾诱导血管收缩后，研究酸中毒的影响。呼吸性酸中毒引起短暂性压抑，随后收缩张力恢复。新生儿发育性张力的下降幅度大于成人。酸中毒期间pHi的下降在两个年龄组中是相似的。酸中毒时fura-2荧光比值升高，新生儿与成人相似。这些数据表明，酸中毒在过早血管中的血管松弛作用大于成熟血管。新生儿更大的血管舒张不能用pHi或[Ca]i反应的差异来解释。

This study investigated the effect of respiratory acidosis on intracellular pH (pH_i), intracellular calcium concentration ( [Ca] _i), and vascular contraction in the aorta and mesenteric artery of the newborn and adult rabbit. Isometric tension was measured in the isolated ring preparation. After the vascular contraction was induced with 50mM KCl, the effect of acidosis was studied. Respiratory acidosis caused transient depression followed by a recovery of contractile tension. The decrease of developed tension in the newborn was greater than that in the adult. The decrease in pHi during acidosis was similar in the two age groups. The fura-2 fluorescence ratio increased during acidosis and the increase in the newborn was was similar to that in the adult. These data suggest that the vasorelaxant effect of acidosis in the premature vessels was greater than in the mature vessels. The greater vasodilation in the newborn cannot be explained by the difference in pHi or [Ca]i responses.