Joseph S Adorante

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Intracellular microelectrode techniques and intracellular pH (pHi) measurements using the fluorescent dye 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein (BCECF) were employed to characterize an electrogenic bicarbonate transport mechanism at the apical membrane of the frog retinal pigment epithelium (RPE). Reductions in apical concentrations of both(More)
Changes in retinal pigment epithelial (RPE) cell volume were measured by monitoring changes in intracellular tetramethylammonium (TMA) using double-barreled K-resin microelectrodes. Hyperosmotic addition of 25 or 50 mM mannitol to the Ringer of the apical bath resulted in a rapid (approximately 30 s) osmometric cell shrinkage. The initial cell shrinkage was(More)
The solute and water transport properties of the bovine ciliary epithelium were studied using isolated pigmented (PE) and nonpigmented (NPE) cells. It was shown that these cells were functionally coupled by demonstrating dye diffusion between paired PE and NPE cells after microinjection of lucifer yellow. Electronic cell sizing was used to measure cell(More)
If the extracellular fluid is left unbuffered, dynamic membrane potential changes in the red blood cell may be determined from external pH readings. For some types of experiments it is necessary to accelerate H+ equilibration by adding minute amounts of hydrogen carriers. The method is independent of hematocrit over a wide range of membrane potential(More)
To measure changes in cell water during cell volume regulation, retinal pigment epithelial cells were loaded with tetramethylammonium (TMA). Regulatory volume decrease (RVD) in TMA-loaded retinal pigment epithelial (RPE) cells was measured using double-barreled K(+)-specific microelectrodes. Hyposmotic removal of 12.5 mM NaCl from the apical bath caused(More)
Exposure of Amphiuma red blood cells to millimolar concentrations of N-ethylmaleimide (NEM) resulted in net K loss. In order to determine whether net K loss was conductive or was by electroneutral K/H exchange or KCl cotransport, studies were performed evaluating K flux in terms of the thermodynamic forces to which K flux by the above pathways should(More)
To study the net solute and water efflux pathways of the ciliary epithelium we employed a cultured human NPE cell line. Because of the possible relationship between transepithelial ion and water flux and cell volume regulation, the ion efflux pathways mediating regulatory volume decrease (RVD) were investigated. Osmotic swelling of NPE cells was followed by(More)
Na(+)-K(+)-ATPase pump failure during either anoxia or ouabain perfusion induces rapid axonal depolarization by dissipating ionic gradients. In this study, we examined the interplay between cation and anion transporting pathways mediating axonal depolarization during anoxia or selective Na(+)-K(+)-ATPase inhibition. Compound resting membrane (V(m))(More)
23Na nuclear magnetic resonance (NMR) and conventional chemical methods were employed to measure Na+ fluxes in Amphiuma red blood cells (RBC) during volume regulation. Paramagnetic shift reagents [dysprosium triethylenetetraminehexaacetic acid (DyTTHA) and dysprosium tripolyphosphate (Dy(TPP)2)] were used to alter extracellular Na+ magnetic resonance. Data(More)
Human red blood cells pretreated with low-ionic-strength solutions and resuspended in saline respond biphasically to extracellular Ca. At first, addition of Ca causes a large transient K efflux of as much as 600 mM . liter cell H2O-1 . h-1; this is followed by a decrease in K flux below control levels. The first phase (phase I) resembles the Gardos effect(More)