The M-1 cell line, derived from the mouse cortical collecting duct (CCD), is being used as a mammalian model of the CCD to study Na+ transport. The present studies aimed to further define the role of various hormones in affecting Na+ transport in M-1 cells grown in defined media. M-1 cells on permeable support, in serum-free media, developed amiloride-sensitive current 4-5 days after seeding. A...

Mechanism of transport of the alkylating agent cyclophos phamide-' 4C was investigated in L5 178Y lymphoblasts in vitro. A time course of cyclophosphamide uptake showed a rapid, initial phase, probably due to binding of drug to the cell surface. Subsequent uptake into the cells was carrier mediated and consisted of two components. Analysis of cyclophos phamide uptake over a 40-fold range of dru...

Futile plasma membrane cycling of ammonium (NH4 ) is characteristic of low-affinity NH4 + transport, and has been proposed to be a critical factor in NH4 + toxicity. Using unidirectional flux analysis with the positronemitting tracer N in intact seedlings of barley (Hordeum vulgare L.), it is shown that rapid, futile NH4 + cycling is alleviated by elevated K supply, and that low-affinity NH4 + ...

The neuropeptide CAP2b stimulates fluid transport obligatorily via calcium entry, nitric oxide, and cGMP in Drosophila melanogaster Malpighian (renal) tubules. We have shown by RT-PCR that the Drosophila L-type calcium channel alpha1-subunit genes Dmca1D and Dmca1A (nbA) are both expressed in tubules. CAP2b-stimulated fluid transport and cytosolic calcium concentration ([Ca2+]i) increases are i...

Futile plasma membrane cycling of ammonium (NH4+) is characteristic of low-affinity NH4+ transport, and has been proposed to be a critical factor in NH4+ toxicity. Using unidirectional flux analysis with the positron-emitting tracer 13N in intact seedlings of barley (Hordeum vulgare L.), it is shown that rapid, futile NH4+ cycling is alleviated by elevated K+ supply, and that low-affinity NH4+ ...

Glucose addition to glucose-starved Saccharomyces cerevisiae cells triggers a quick and transient influx of calcium from the extracellular environment. In yeast at least two different carrier systems were identified: a high affinity system, requiring Cch1 channel, and a low affinity system. Here we report that another calcium transport system exists in yeast, not yet identified, that can substi...

Pedersen, Peter Steen, Ole Frederiksen, Niels-Henrik Holstein-Rathlou, Per Leganger Larsen, and Klaus Qvortrup. Ion transport in epithelial spheroids derived from human airway cells. Am. J. Physiol. 276 (Lung Cell. Mol. Physiol. 20): L75–L80, 1999.—In the present study, we describe a novel three-dimensional airway epithelial explant preparation and demonstrate its use for ion transport studies ...

Sodium transport by erythrocyte membranes was studied in hypertensive and normotensive humans and in spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY). The rate constants of sodium efflux were increased in both hypertensive humans and rats, and this increase was due mostly to an increase in the ouabain-resistant component of efflux. Both the furosemide-sensitive and...

Understanding the transport and behavior of bacteria in the environment has broad implications in diverse areas, ranging from agriculture to groundwater quality, risk assessment, and bioremediation. The ability to reliably track and enumerate specific bacterial populations in the context of native communities and environments is key to developing this understanding. We report a novel bacterial ...

Sumtmary. The influence of several tincoutplers of oxidative phosphorvlatioii and inhibitors of terminal electron transport was stutdied on absorption and long distance transport of both K and Cl at concentrations within each range of the dual isotherm typical of ion uptake by maize roots. At low concentrations in the range of system 1, the system considered to implement ion movement through th...