These experiments evaluated salt transport processes in isolated cortical thick limbs of Henle (cTALH) obtained from mouse kidney. When the external solutions consisted of Krebs-Ringer bicarbonate (KRB), pH 7.4, and a 95% O2-5% CO2 gas phase, the spontaneous transepithelial voltage (Ve, mV, lumen-to-bath) was approximately mV; the net rate of Cl- absorption (JnetCl) was approximately 3,600 pmol...

INTRODUCTION The objective of the study is to determine the level of agreement between measured total carbon dioxide (TCO2) and calculated bicarbonate (HCO3-) in our laboratory. MATERIALS AND METHODS TCO2 and HCO3- values of 1820 samples drawn at the same time from the patient were compared. TCO2 from venous samples was measured on Dimension RxL while HCO3- was obtained from arterial blood ga...

One of the major tasks of the renal proximal tubule is to secrete acid into the tubule lumen, thereby reabsorbing approximately 80% of the filtered HCO3- as well as generating new HCO3- for regulating blood pH. This review summarizes the cellular and molecular events that underlie four major processes in HCO3- reabsorption. The first is CO2 entry across the apical membrane, which in large part ...

The effects of hypercapnia (1% CO2), and the independent effects of changes in extracellular pH (pHe), PCO2 and [HCO3-] on intracellular pH (measured by the DMO method) and lactate metabolism (measured by utilization of 14C-labelled lactate), were examined in rainbow trout hepatocytes in vitro. Simulated uncompensated hypercapnia (high PCO2, low pHe, moderately increased [HCO3-] led to a substa...

1. Aedes dorsalis larvae are one of the few organisms capable of inhabiting hypersaline NaHCO3-CO3 lakes. Under laboratory conditions larvae can survive and develop normally in saline media with pH values of 10-5, HCO3~ concentrations of 250 mM, or CO3 ~ concentrations of 100 mM. 2. Despite ingestion of alkaline media at a rate equal to 130% of larval body wt/day, these insects regulated haemol...

Several studies suggest the involvement of Na+ and HCO3- transport in the formation of cerebrospinal fluid. Two Na+-dependent HCO3- transporters were recently localized to the epithelial cells of the rat choroid plexus (NBCn1 and NCBE), and the mRNA for a third protein was also detected (NBCe2) (Praetorius J, Nejsum LN, and Nielsen S. Am J Physiol Cell Physiol 286: C601-C610, 2004). Our goal wa...

The distribution of Na(+)-independent Cl(-)-HCO3- exchange was studied in individual intercalated cells from in vitro perfused rabbit outer CCDs using dual excitation laser scanning confocal microscopy by measuring the pHi response to sequential removal of Cl- from both sides of the tubule. Three patterns of intracellular pH (pHi) response were observed. 39% of intercalated cells had only apica...

Ureagenesis in the liver consumes up to 1,000 mmol of HCO3-/day in humans as a result of 2NH4+ + 2HCO3- --> urea + CO2 + 3H2O. Whether the liver contributes to the regulation of acid-base equilibrium by controlling the rate of ureagenesis and, therefore, HCO3- consumption in response to changes in plasma acidity has not been adequately evaluated in humans. Rates of ureagenesis were measured in ...

[1] While much of the dissolved organic carbon (DOC) within rivers is destined for mineralization to CO2, a substantial fraction of riverine bicarbonate (HCO3 ) flux represents a CO2 sink, as a result of weathering processes that sequester CO2 as HCO3 . We explored landscape-level controls on DOC and HCO3 flux in subcatchments of the boreal, with a specific focus on the effect of permafrost on ...

Bicarbonate provides the dominant pH buffer of the cochlear fluids. In the present study, perilymph bicarbonate concentration was manipulated during which endocochlear potential, cochlear fluids pH and cochlear sensitivity to sounds were monitored. Perilymphatic perfusion of medium containing elevated HCO3, at higher pH than normal, produced a decrease in endolymph pH. Similarly, perfusion of n...