Sodium-linked and sodium-independent HCO3-/Cl- antiport was measured under different conditions in a number of cell lines. Transport of HCO3- was estimated from its effect on intracellular pH (pHi) measured with the fluorescent probe 2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein. The associated ion fluxes were estimated from the transport of 36Cl- and 22Na+. Na+-dependent and Na+-independent H...

Hydroponic culture solutions containing bicarbonate (HCO3 ) may be used to screen crops such as soybeans (Glycine max) for resistance to iron (Fe) deficiency or chlorosis. Some successful methods use sodium bicarbonate (NaHCO3) in combination with elevated partial pressures of carbon dioxide (CO2) to buffer pH and elevate bicarbonate. Replacing NaHCO3 with magnesium bicarbonate [Mg(HCO3)2] as t...

Electrogenic cotransport of Na+ with HCO3- has been reported in numerous tissues. It has always been shown with a net transfer of negative charge, but in some situations achieves net outward transport of both species with a stoichiometry of at least three HCO3- ions per Na+ ion (3:1), and in other situations achieves net inward transport of both species and has a stoichiometry of at most two HC...

The role of buffering of the high pericardial fluid [HCO3~] of the turtle, Chrysemys picta bellii Gray, was evaluated during prolonged anoxia at 3 and 10°C. At 3°C, pericardial fluid samples were collected from groups of animals after 0, 1, 2, 4 and 8 weeks of anoxia, and the ionic composition of these samples was compared to plasma values from the same animals. At 10 °C, pericardial and plasma...

The cortical collecting duct (CCD) B cell possesses an apical anion exchanger dissimilar to AE1, AE2, and AE3. The purpose of these studies was to characterize this transporter more fully by examining its regulation by CO2 and HCO3. We measured intracellular pH (pHi) in single intercalated cells of in vitro microperfused CCD using the fluorescent, pH-sensitive dye, 2',7'-bis(2-carboxyethyl)-5(6...

Anion transport by the colonic mucosa maintains the hydration and pH of the colonic lumen, and its disruption causes a variety of diarrheal diseases. Cholinergic agonists raise cytosolic Ca2+ levels and stimulate anion secretion, but the mechanisms underlying this effect remain unclear. Cholinergic stimulation of anion secretion may occur via activation of Ca2+-activated Cl- channels (CaCCs) or...

In mammals, Ca2+ and HCO3- ions play a critical role in the regulation of sperm function, most likely by regulation of cAMP levels. Mammalian germ cells contain a soluble adenylyl cyclase (sAC) with properties distinct from the well characterized membrane-bound enzymes Here we investigated whether the cyclase expressed in mature spermatozoa has the properties of sAC and whether it is regulated ...

To evaluate ion transport mechanisms in bile duct epithelium (BDE), BDE cells were isolated from bile duct-ligated rats. After short-term culture pHi was measured with a single cell microfluorimetric set-up using the fluorescent pHi indicator BCECF, and calibrated with nigericin in high K+ concentration buffer. Major contaminants were identified using vital markers. In HCO3(-)-free media, basel...

Arterial base deficit/excess (BD/E) is commonly used marker of metabolic acidosis in critically ill patients, but requires an arterial puncture and blood gas analysis. We hypothesized that serum bicarbonate (HCO3), which can be routinely obtained, strongly correlates with arterial BD/E and provides equivalent predictive information. In addition, we evaluated predictive value of simplified acute...

B romide (Br) causes positive interference with all clinical laboratory methods for the detenmination of serum Cl (1 .2). Interference with Cl measurement is much greater with ion-selective electrode (ISE) technology (1 .3) than with coubometry (1 -4). We recently described a patient ingesting therapeutic amounts of pynidostigmine Br (MestInon1 , containing 1 8.4 mg of Br [30.6%j per 60-mg tabl...