The role of Ca2+/calmodulin-dependent processes in the activation of the Na+/H+ antiport of primary cultures of rat aortic smooth muscle was studied using 22Na+ uptake and measurement of intracellular pH (pHi) with the fluorescent pH dye 2',7'-bis-(2-carboxyethyl)-5(and 6)-carboxyfluorescein. Antiport activation following exposure to serum and by the induction of an intracellular acidosis could...

The osmoregulation of the nauplius of the brine shrimp, Artemia salina, was investigated using micropuncture and microanalytical techniques. The naupliar body fluid, hemolymph was hyposmotic to and had lower Na concentrations than the suspending medium for the range of medium salinities from 80 to 4,900 mM NaCl. In medium containing 20 mM NaCl, the hemolymph was hyperosmotic to the medium, with...

Diabetes mellitus is associated with important changes in renal hemodynamics and transport function. Disturbances in solute transport have also been characterized in nonrenal tissues during hyperglycemia and insulinopenia. The purpose of this study was to determine if diabetes is associated with adaptive changes in function of the brush-border membrane of the proximal tubule. We studied Na+ and...

Isolated adult rat heart cells in suspension were loaded with sodium by incubation with ouabain in the absence of calcium for 30 minutes. Addition of low levels of calcium induced accelerated rates of sodium influx and efflux, as measured with 22Na. The magnitude of calcium-induced 22Na efflux was 50-fold greater than the net rate of calcium uptake and required extracellular sodium, but not ext...

To measure the influx of Na+ and other ions through the light-dependent permeability of photoreceptors, we superfused the isolated retina of the toad, Bufo marinus, with a low-Ca2+ (10(-8) M), low-Cl- Ringer's solution containing 0.5 mM ouabain. Under these conditions, the membrane potential of the rod is near zero and there is no light-induced potential change either in the rod or in more prox...

The influx of 22Na into the smooth muscle cells of incubated rat tail arteries was measured directly, in the presence and absence of 2.8 X 10(-7) M D-aldosterone. During the analysis, extracellular 22Na and 23Na were removed by incubation of the tissue in sodium-free lithium-substituted physiological salt solution at less than 3 degrees C. Aldosterone increased the influx rate coefficient by 10...

We have examined the ion transport properties and the inhibition of rat liver mitochondrial substrate oxidation by the antibiotic W341C. W341C was able to transport 22Na+ and 42K+ across a bulk carbon tetrachloride layer. A preference was shown for K+ transport. With equal molar antibiotic concentrations, W341C transported 42K+ at a greater rate than the K+-selective ionophore nigericin, but tr...

The REPRO-TDE test was performed at a depth of about 400 m in the ONKALO underground research facility Finland. Synthetic groundwater containing radionuclide tracers [tritiated water tracer (HTO), 36Cl, 22Na, 133Ba, and 134Cs] circulated for 4 years packed-off interval injection borehole. Tracer activities were additionally monitored two observation boreholes. subject modeling exercise by SKB G...

The effects of compounds previously described to inhibit anion transport were tested for their ability to inhibit anion antiport in Vero cells as measured by uptake of 36Cl- by chloride self-exchange and as bicarbonate-linked uptake of 22Na+. While 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid inhibited both processes, ethacrynic acid and probenecid selectively inhibited the uptake of 36Cl-....