Laboratory of Endothelial Function, Department of Surgery and Anatomy, School of Medicine, University of São Paulo, Ribeirão Preto, SP, Brazil.
PLoS One. 2013 May 17;8(5):e62887. doi: 10.1371/journal.pone.0062887. Print 2013.
It has been known for more than a century that pH changes can alter vascular tone. However, there is no consensus about the effects of pH changes on vascular response. In this study, we investigated the effects of extracellular pH (pHo) changes on intracellular pH (pHi) and intracellular nitric oxide concentration ([NO]i) in freshly isolated endothelial cells and cross sections from rat aorta.
The HCl was used to reduce the pHo from 7.4 to 7.0 and from 7.4 to 6.5; the NaOH was used to increase the pHo from 7.4 to 8.0 and from 7.4 to 8.5. The fluorescent dyes 5-(and-6)-carboxy SNARF-1, acetoxymethyl ester, acetate (SNARF-1) and diaminofluorescein-FM diacetate (DAF-FM DA) were employed to measure the pHi and [NO]i, respectively. The fluorescence intensity was measured in freshly isolated endothelial cells by flow cytometry and in freshly obtained aorta cross sections by confocal microscopy.
The endothelial and vascular smooth muscle pHi was increased at pHo 8.5. The extracellular acidification did not change the endothelial pHi, but the smooth muscle pHi was reduced at pHo 7.0. At pHo 8.5 and pHo 6.5, the endothelial [NO]i was increased. Both extracellular alkalinization and acidification increased the vascular smooth muscle [NO]i.
Not all changes in pHo did result in pHi changes, but disruption of acid-base balance in both directions induced NO synthesis in the endothelium and/or vascular smooth muscle.
一个多世纪以来，人们已经知道 pH 值的变化可以改变血管张力。然而，对于 pH 值变化对血管反应的影响，尚无共识。在这项研究中，我们研究了细胞外 pH 值（pHo）变化对新鲜分离的内皮细胞和大鼠主动脉横切片中细胞内 pH 值（pHi）和细胞内一氧化氮浓度 ([NO]i) 的影响。
使用 HCl 将 pHo 从 7.4 降低至 7.0 和 6.5；使用 NaOH 将 pHo 从 7.4 增加至 8.0 和 8.5。使用荧光染料 5-(和-6)-羧基 SNARF-1，乙氧基甲酯，乙酸盐（SNARF-1）和二氨基荧光素 FM 二乙酸酯（DAF-FM DA）分别测量 pHi 和 [NO]i。通过流式细胞术测量新鲜分离的内皮细胞中的荧光强度，并通过共聚焦显微镜测量新鲜获得的主动脉横切片中的荧光强度。
pHo 为 8.5 时，内皮和血管平滑肌的 pHi 增加。细胞外酸化不会改变内皮 pHi，但 pHo 为 7.0 时平滑肌 pHi 降低。在 pHo 8.5 和 pHo 6.5 时，内皮 [NO]i 增加。细胞外碱化和酸化均增加血管平滑肌 [NO]i。
并非所有 pHo 的变化都导致 pHi 的变化，但酸碱平衡的双向破坏诱导内皮和/或血管平滑肌中一氧化氮的合成。
