Acid-base regulation of ion transport in rabbit ileum in vitro.
Acid-base regulation of ion transport in rabbit ileum in vitro.
复制标题
体外兔回肠离子转运的酸碱调节。
DOI：
10.1016/0016-5085(90)91240-7
复制
发表时间：
1990
期刊：
影响因子：
29.4
通讯作者：
Sellin,JH
中科院分区：
文献类型：
--
作者：
DeSoignie,R;Sellin,JH
Changes in acid-base balance have a major influence on ion transport in the ileum. The goals of the present study were to delineate (a) the specific transport processes most affected by changes in acid-base metabolism, (b) the individual roles of pH, PCO2, and concentration of HCO3−in modulating ion transport, and (c) the relationship between acid-base sensitive and other ion-transport systems. Ion transport and electrical parameters were measured in rabbit ilea in vitro under short-circuit conditions with systematic variations of pH, PCO2, and concentrations of HCO3−. Increasing HCO3−concentrations, with constant PCO2and increasing pH, caused a decrease in electroneutral Na+and Cl−absorption. At 5 mmol/L HCO3−, net fluxes of Na+and Cl−were 5.9 ± 1.4 and 4.5 ± 1.1 μEq · cm−2· h−1, while at 50 mmol/L HCO3−, net Na+and Cl−fluxes were 0.7 ± 0.7 and 0.2 ± 0.6 μEq · cm−2· h−1. Transepithelial HCO3−-gradient experiments suggested that serosal HCO3−was the principal factor. Changes in PCO2showed a complex biphasic response, increasing net Cl−flux as PCO2increased from 11–30 mm Hg in 5 mmol/L HCO3−; net Na−flux increased as PCO2was changed from 36 to > 100 mm Hg in 22 mmol/L HCO3−. In contrast, increasing pH in a bicarbonate-freeN-2-hydroxyethylpiperazine-N′-2 = ethane sulfonic acid buffer did not significantly alter Na+transport. Acidbase stimulated Na+absorption was inhibited by 10−3mol/L amiloride, but not by bumetanide, consistent with the involvement of Na+-H+exchange rather than Na+-Cl−cotransport. Epinephrine did not increase Na+absorption under acid-base stimulated conditions, but glucose did, suggesting that the ratelimiting step for electroneutral absorptive processes under these conditions occurs at the apical rather than the basolateral membrane. Combining all experiments, a significant correlation existed between net flux of Na+and HCO3−concentration (r= −0.72,P< 0.05) and between net flux of Na+and pH (r= −0.68,P< 0.01). Chloride absorption was correlated with pH (r= 0.72,P< 0.01). These results suggest a profound regulatory role for acid-base balance in electroneutral Na+-Cl−transport in rabbit ileum in vitro.
