The Na+/H+ antiport is an important regulator of cellular volume, pH and Na+ concentration in mammalian cells. The stoichiometry of this antiporter has previously been shown to be a 1:1 exchange of internal H+ for external Na+. We have investigated this stoichiometry in human leucocytes by using a novel intracellular pH-clamping technique and measuring 22Na+ influx and H+ efflux in the same cel...

Na+/H+ antiporters in the CPA1 branch of the cation proton antiporter family drive the electroneutral exchange of H+ against Na+ ions and ensure pH homeostasis in eukaryotic and prokaryotic organisms. Although their transport cycle is overall electroneutral, specific partial reactions are electrogenic. Here, we present an electrophysiological study of the PaNhaP Na+/H+ antiporter from Pyrococcu...

Na+/H+ antiport is a major determinant of intracellular pH (pHi) and also plays an important role in the maintenance of cellular volume. Na+/H+ exchange through NHE-1, the ubiquitous isoform of the antiporter, is accelerated by cytosolic acidification and also by osmotically induced cell shrinking, thereby promoting recovery of the physiological pHi and volume, respectively. Although hydrolysis...

BACKGROUND Sodium/proton-antiporters (Nha) are known to play an important role in pH- and Na+-homeostasis. In microorganisms several types with different capacity, affinity and selectivity for Na+ and Li+ exist. The homeostasis system of E. coli, NhaA and NhaB, is well researched, but the function of other types of Na+/H+-antiporters like NhaD is yet to be fully understood. Since several antipo...

Na+/H+ exchange in vertebrates is thought to be electroneutral and insensitive to the membrane voltage. This basic concept has been challenged by recent reports of antiport-associated currents in the turtle colon epithelium (Post and Dawson, 1992, 1994). To determine the electrogenicity of mammalian antiporters, we used the whole-cell patch clamp technique combined with microfluorimetric measur...

Voltage-activated H(+)-selective currents were studied in cultured adult rat alveolar epithelial cells and in human neutrophils using the whole-cell configuration of the patch-clamp technique. The H+ conductance, gH, although highly selective for protons, was modulated by monovalent cations. In Na+ and to a smaller extent in Li+ solutions, H+ currents were depressed substantially and the voltag...

ShaA (sodium/hydrogen antiporter, previously termed YufT [or NtrA]), which is responsible for Na(+)/H(+) antiporter activity, is considered to be the major Na(+) excretion system in Bacillus subtilis. We found that a shaA-disrupted mutant of B. subtilis shows impaired sporulation but normal vegetative growth when the external Na(+) concentration was increased in a low range. In the shaA mutant,...