The effects of changes in peritubular pH, carbon dioxide tension (PCO2), and HCO3- concentration on net HCO3- transport was examined in in vitro perfused cortical collecting tubules (CCTs) from unpretreated New Zealand white rabbits. Lowering peritubular HCO3- concentration and pH by reciprocal replacement of HCO3- with Cl-, significantly stimulated net HCO3- absorption. Lowering peritubular HC...

We have studied lactic acid transport in the fast mouse extensor digitorum longus muscles (EDL) by intracellular and cell surface pH microelectrodes. The role of membrane-bound carbonic anhydrases (CA) of EDL in lactic acid transport was investigated by measuring lactate flux in muscles from wildtype, CAIV-, CAIX- and CAXIV-single ko, CAIV-CAXIV double ko and CAIV-CAIX-CAXIV-triple ko mice. Thi...

Plasma [Na], [K], and [Cl~] were measured on blood sampled periodically from turtles submerged in Na-equilibrated (low-Oa) or air-equilibrated (high-Og) water. Plasma osmolality and total [Ca ] and [Mg] were measured on selected samples. Previously we reported that a severe metabolic acidosis developed under these conditions; in low-O2 turtles, plasma [lactate"], rising to over 200 m-equiv/1, w...

Bestrophin-1 (Best1) is a Cl(-) channel that is linked to various retinopathies in both humans and dogs. Dysfunction of the Best1 Cl(-) channel has been proposed to cause retinopathy because of altered Cl(-) transport across the retinal pigment epithelium (RPE). In addition to Cl(-), many Cl(-) channels also transport HCO3(-). Because HCO3(-) is physiologically important in pH regulation and in...

Address for Correspondence:Masaji Mochizuki, Minami-11, Nishi-20, 4-23 Chuo-Ku, Sapporo 064-0811, Japan The bicarbonate concentration in plasma , [HCO3], has a PCO2-dependent component, [HCO3]*, and a metabolic component, [HCO3]. The [HCO3]* in elderly patients and volunteers was expressed by an exponential function of PCO2 obtained by analysis of the venous-arterial (a-v) difference in [HCO3]....

We investigated effects of molecular hydrogen (H2) supplementation on acid-base status, pulmonary gas exchange responses, and local muscle oxygenation during incremental exercise. Eighteen healthy, trained subjects in a randomized, double-blind, crossover design received H2-rich calcium powder (HCP) (1500 mg/day, containing 2.544 µg/day H2) or H2-depleted placebo mg/day) for three consecutive d...

TO THE EDITOR: This debate (1, 4) focused on whether the increase in plasma [lactate] was the sole contributor to the acidosis associated with exercise at sufficiently high intensities to generate increased plasma [lactate ]. It remains puzzling that many physiologists continue to compare plasma “acidbase” status (pH, PCO2, [HCO3 ]) with whole blood (not plasma) measures of [lactate ], thus equ...

Reduced gastrointestinal HCO3- secretion contributes to malabsorption and obstructive syndromes in cystic fibrosis. The apical HCO3- transport pathways in these organs have not been defined. We therefore assessed the involvement of apical Cl-/HCO3- exchangers and anion conductances in basal and cAMP-stimulated duodenal HCO3- secretion. Muscle-stripped rat and rabbit proximal duodena were mounte...

Unidirectional Na and Cl~ fluxes, net fluxes of Na, Cl~, other ions, titratable acid (TA), ammonia and acidic equivalents (net H) across the gills, together with the comparable renal fluxes, were monitored throughout a 24-h period after exhaustive exercise (simple chasing) in the rainbow trout. The gills were the major site of flux. The renal excretion of [TA—HCO3~], ammonia, lactate and most e...

Hemorrhagic shock reflects low tissue perfusion that is inadequate to maintain normal metabolic functions. Often associated with this condition are impairments in cellular oxygen delivery and utilization. Rat strains divergent in their running endurance have been artificially selected over 12 generations. As these rats bred for high (HCR) vs low (LCR) aerobic running capacity have greater tissu...