Genistein, an isoflavone inhibitor of tyrosine-specific protein kinases, was shown to specifically block the 22Na+ influx through voltage-sensitive Na+ channels in cultured rat brain neurons, whereas other tyrosine kinase antagonists such as lavendustin A, compound 5, tyrphostin A47 and an erbstatin analog were inactive at concentrations known to block kinase activity in other neuronal systems....

PURPOSE To investigate the role of externally facing membrane protein sulfhydryl groups in controlling lens permeability and transparency using the impermeant sulfhydryl complexing agent p-chloromercuriphenyl sulfonate (pCMPS). METHODS Membrane permeability changes were studied by measuring lens voltage and resistance. Ion movements were monitored by measuring 22Na+ and 45Ca2+ fluxes, and int...

There are several meteoritic noble gas components whose isotopic abundances are distinctly different from the solar abundance. One of these components, Ne-E(L), is a 22Ne-rich component carried by presolar graphite. Neon-22 is dominantly from the radiogenic decay of 22Na (T1/2 = 2.6 a), but it also contains 22Ne produced by 14N(α, γ )18F(e+ν)18O(α, γ )22Ne. The proportions of 22Ne from the two ...

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...