Intracellular Ca(2+) plays a fundamental role in regulating cell functions in pulmonary arterial smooth muscle cells (PASMCs). A rise in cytosolic Ca(2+) concentration ([Ca(2+)](cyt)) triggers pulmonary vasoconstriction and stimulates PASMC proliferation. [Ca(2+)](cyt) is increased mainly by Ca(2+) release from intracellular stores and Ca(2+) influx through plasmalemmal Ca(2+)-permeable channel...

Acid-activated chloride currents have been reported in several cell types and may play important roles in regulation of cell function. However, the molecular identities of the channels that mediate the currents are not defined. In this study, activation of the acid-induced chloride current and the possible candidates of the acid-activated chloride channel were investigated in human nasopharynge...

The effects of transport inhibitors on the movements of oxalate and chloride across the isolated short circuited rabbit colon were studied. Net oxalate absorption was shown in this species and was shown to be an energy dependent process as indicated by its sensitivity to 2-4 dinitrophenol (DNP) 10(-4)M. Mucosal addition of 4-acetamido-4-isothiocyano-2,-stilbene-2,2'-disulfonic acid (SITS) 10(-4...

Peroxynitrite (ONOO(-)), a reactive oxidant produced by the reaction between nitric oxide and superoxide, was found to diffuse into the platelet cytosol and inhibit arachidonic acid-induced platelet aggregations with IC(50) value of 5.8 +/- 1.2 microM. A fluorescence assay established that ONOO(-) diffused into the platelet cytosol in a manner that was inhibited (50-70%) by 4, 4'-diisothiocyana...

In proximal tubules isolated from chicken superficial loopless reptilian-type nephrons, intracellular pH (pHi), measured with pH-sensitive fluorescent dye 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein, was ∼7.1-7.2 under control conditions ( N-2-hydroxyethylpiperazine- N'-2-ethanesulfonic acid-buffered medium with pH 7.4 at 37°C), and was reduced to ∼6.9 in response to NH4Cl pulse. The rate o...

Anion conductance across the Drosophila melanogaster Malpighian (renal) tubule was investigated by a combination of physiological and transgenic techniques. Patch-clamp recordings identified clusters of 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS)-sensitive "maxi-chloride" channels in a small domain of the apical membrane. Fluid secretion assays demonstrated sensitivity to the chlori...