To examine the mechanism by which mineralocorticoids regulate HCO3- absorption in the rabbit inner stripe of the outer medullary collecting duct, we microfluorometrically measured intracellular pH (pHi) in in vitro perfused tubules using 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein (BCECF) assaying the apical and basolateral membrane H+/OH-/HCO3- transport processes in three groups of animal...

Carbonic anhydrase enzymes (CAs) catalyse the reversible hydration of CO2 to H+ and HCO3- ions. This catalysis is proposed to be harnessed by acid/base transporters, to facilitate their transmembrane flux activity, either through direct protein-protein binding (a 'transport metabolon') or local functional interaction. Flux facilitation has previously been investigated by heterologous co-express...

In this study, geophysics, geochemistry, and geostatistical techniques were integrated to assess seawater intrusion in Kapas Island due to its geological complexity and multiple contamination sources. Five resistivity profiles were measured using an electric resistivity technique. The results reveal very low resistivity <1 Ωm, suggesting either marine clay deposit or seawater intrusion or both ...

Properties of adenosine triphosphatases (ATPases) in the choroid plexus of rabbit cerebral ventricles were investigated using tissue homogenates and subcellular fractions. Na,K-ATPase or HCO3-ATPase activity of choroid plexus was significantly lower than that of the brain or the kidney, respectively. Among the homogenates of choroid plexus from the lateral, third and fourth ventricles, there we...

The activity of pyruvate dehydrogenase complex (PDC) purified from pig kidney cortex was found to be affected by various uni- and bi-valent ions. At a constant strength of 0.13 M at pH 7.8, K+, Na+, Cl-, HCO3- and HPO4(2-) had significant effects on the activity of PDC: Na+, K+ and HPO4(2-) stimulated, but HCO3- and Cl- inhibited. The stimulatory effect of Na+ was mediated by a change in the Vm...

The purposes of this study were to determine 1) the presence of the major ion transport activities that regulate cytoplasmic pH (pH(c)) in cat pulmonary artery smooth muscle cells, i.e., Na+/H+ and the Na+-dependent and -independent Cl-/HCO3- exchange, 2) whether pH(c) changes in cells from small (SPAs) and large (LPAs) pulmonary arteries during hypoxia, and 3) whether changes in pH(c) are due ...

Lazrak, Ahmed, Ulrich Thome, Carpantanto Myles, Janice Ware, Lan Chen, Charles J. Venglarik, and Sadis Matalon. cAMP regulation of Cl and HCO3 secretion across rat fetal distal lung epithelial cells. Am J Physiol Lung Cell Mol Physiol 282: L650–L658, 2002. First published December 7, 2001; 10.1152/ajplung.00370.2001.—We isolated and cultured fetal distal lung epithelial (FDLE) cells from 17to 1...

The acid- and volume-sensitive TASK2 K+ channel is strongly expressed in renal proximal tubules and papillary collecting ducts. This study was aimed at investigating the role of TASK2 in renal bicarbonate reabsorption by using the task2 -/- mouse as a model. After backcross to C57BL6, task2 -/- mice showed an increased perinatal mortality and, in adulthood, a reduced body weight and arterial bl...

Congenital chloride diarrhea (CCD) is a rare autosomal recessive disorder, characterized by watery stools with C1- concentration around 150 meq/liter. We have perfused the colon of three patients and their three healthy siblings with different salt solutions containing 36C1- to determine the nature of the colonic defect in CCD. In the controls, net absorption of Na+ and C1- occurred against ste...