Benedetti A, Di Sario A, Svegliati Baroni G, Jezequel A M
Clinica di Gastroenterologia, University of Ancona, School of Medicine, Italy.
Hepatology. 1995 Nov;22(5):1488-98.
Transforming growth factor beta 1 (TGF beta 1) is involved in promoting cell death by apoptosis in the liver, whereas the activation of Na+/H+ exchanger has been related to cell proliferation. The aim of this study was to gain information on the effects of TGF beta 1 on intracellular pH and Na+/H+ exchange activity in isolated periportal (PP) and perivenular (PV) rat hepatocytes using the pH-sensitive dye BCECF in a perfused subconfluent hepatocyte monolayer. Steady-state intracellular pH (pHi) in a bicarbonate-free solution (HEPES) were 7.17 +/- 0.031 in PP and 7.15 +/- 0.041 in PV cells. Treatment with TGF beta 1 (120 pmol/L) for 7 hours increased the number of apoptotic bodies by 25% and 38%, and decreased steady-state pHi to 7.11 +/- 0.018 (P = .05) and to 7.07 +/- 0.021 (P < .02), respectively, in PP and PV hepatocytes. In HEPES, cells recovered from an acid load, extruding protons at a rate (JH) of 4.85 +/- 1.01 mmol/L/min in PP cells and of 4.91 +/- 0.99 mmol/L/min in PV hepatocytes. This recovery appeared amiloride inhibitable (1 mmol/L). Culture with TGF beta 1 for 7 hours induced (in HEPES) a decrease of pHi recovery rate from an acid load more in PV (by 46%) than in PP hepatocytes (by 35%, P < .05). Acute administration of epidermal growth factor (EGF) (10 to 100/mL) induced an increase in Na+/H+ exchange activity by 32% and 27%, respectively, in PP and PV cells compared with controls. In contrast, in cells cultured for 7 hours with 120 pmol/L TGF beta 1, the acute administration of EGF slightly increased Na+/H+ exchange activity (by 18%, P < .05) only in PP cells. This study demonstrates that pHi and Na+/H+ exchange activity are decreased by TGF beta 1, which increases the number of apoptotic bodies in periportal and perivenular rat hepatocyte primary cultures.
转化生长因子β1（TGFβ1）参与促进肝脏细胞通过凋亡而死亡，而Na+/H+交换体的激活则与细胞增殖有关。本研究的目的是利用pH敏感染料BCECF，在灌注的亚汇合肝细胞单层中，获取TGFβ1对分离的大鼠门静脉周围（PP）和肝静脉周围（PV）肝细胞内pH值和Na+/H+交换活性影响的信息。在无碳酸氢盐溶液（HEPES）中，PP细胞的稳态细胞内pH值（pHi）为7.17±0.031，PV细胞为7.15±0.041。用TGFβ1（120 pmol/L）处理7小时后，PP和PV肝细胞中凋亡小体的数量分别增加了25%和38%，稳态pHi分别降至7.11±0.018（P = 0.05）和7.07±0.021（P < 0.02）。在HEPES中，细胞从酸负荷中恢复时，PP细胞以4.85±1.01 mmol/L/分钟的速率（JH）排出质子，PV肝细胞为4.91±0.99 mmol/L/分钟。这种恢复似乎可被氨氯吡脒抑制（1 mmol/L）。用TGFβ1培养7小时（在HEPES中）导致PV肝细胞（降低46%）比PP肝细胞（降低35%，P < 0.05）从酸负荷中恢复pHi的速率下降更多。与对照组相比，急性给予表皮生长因子（EGF）（10至100/ mL）分别使PP和PV细胞中的Na+/H+交换活性增加32%和27%。相反，在使用120 pmol/L TGFβ1培养7小时的细胞中，急性给予EGF仅使PP细胞中的Na+/H+交换活性略有增加（18%，P < 0.05）。本研究表明，TGFβ1降低了pHi和Na+/H+交换活性，增加了大鼠门静脉周围和肝静脉周围肝细胞原代培养物中凋亡小体的数量。
