To clarify the function of the Na(+)-coupled glucose transporter in the regulation of cellular tone of cultured retinal pericytes, we investigated the effects of extracellular glucose concentration on cell size. The surface area and diameter of cultured bovine retinal pericytes under different glucose concentrations were measured by using a light microscope with a digital camera. We also examin...

We recently reported that nitric oxide synthase in the brain can be inhibited not only by nitro-L-arginine (L-NA) but also by its D-enantiomer nitro-D-arginine (D-NA). In the present study, we found that D-NA, when tested in vitro, was 400 times less potent than L-NA. However, when D-NA was injected in vivo, its L-enantiomer, L-NA, was found to rapidly appear in plasma samples (approximately 1 ...

To elucidate the purpose of butterfly puddling, we measured the amounts of Na+, K+, Ca2+, and Mg2+ that were absorbed or excreted during puddling by male Japanese Papilio butterflies through a urine test. All of the butterflies that sipped water with a Na+ concentration of 13 mM absorbed Na+ and excreted K+, although certain butterflies that sipped solutions with high concentrations of Na+ excr...

We previously showed an inverse correlation between membrane cholesterol content and Na-P(i) cotransport activity during the aging process and adaptation to alterations in dietary P(i) in the rat (Levi M, Jameson DM, and van der Meer BW. Am J Physiol Renal Fluid Electrolyte Physiol 256: F85-F94, 1989). The purpose of the present study was to determine whether alterations in cholesterol content ...

22Na+ flux and cytoplasmic pH (pHi) determinations were used to study the reversibility, symmetry, and mechanism of activation of the Na+/H+ exchange system in rat thymic lymphocytes. In acid-loaded cells, the antiport can be detected as an Na+-induced, amiloride-sensitive alkalinization. At pHi greater than or equal to 7.0, amiloride-sensitive net H+ fluxes are not detectable. To investigate w...

Intracellular transport, glycosylation, tetramerization and enzymatic activity of the neuraminidase (NA) of fowl plague virus (FPV) were analysed in vertebrate cells after expression from a vaccinia virus vector. Tetramerization occurred with a half-time of 15 min, whereas passage through the medial Golgi apparatus and transport to the plasma membrane occurred with half-times of 2 and 3 h, resp...

The earliest known ionic event during Friend murine erythroleukemic (MEL) cell differentiation along the erythroid pathway is a 45% drop in intracellular sodium concentration ([Na+]i) due to a decrease in Na+ influx (Lannigan, D. A., and Knauf, P. A. (1985) J. Biol. Chem. 260, 7322-7324). We have analyzed the mechanism of the decreased Na+ influx. The Na+ influx in uninduced cells was insensiti...

Na(+)-Ca2+ exchange has been shown to contribute to reperfusion- and reoxygenation-induced cellular Ca2+ loading and damage in the heart. Despite the fact that both [Na+]i and [Ca2+]i have been documented to rise during ischemia and hypoxia, it remains unclear whether the rise in [Ca2+]i occurring during hypoxia is linked to the rise in [Na+]i via Na(+)-Ca2+ exchange before reoxygenation and ho...

The inactivation of rat renal brush border membrane Na+-H+ exchange by the covalent carboxylate reagent N,N'-dicyclohexylcarbodiimide (DCCD) was studied by measuring 1 mM Na+ influx in the presence of a pH gradient (pHi = 5.5; pHo = 7.5) and H+ influx in the presence of a Na+ or Li+ gradient ([Na+]i = 150 mM; [Na+]o = 1.5 mM). In the presence of DCCD, the rate of Na+ uptake decreased exponentia...

OBJECTIVE Catecholamines that accompany acute physiological stress are also involved in mediating the development of hypertrophy and failure. However, the cellular mechanisms involved in catecholamine-induced cardiac hypertrophy, particularly Ca2+ handling, are largely unknown. We therefore investigated the effects of cardiac hypertrophy, produced by isoprenaline, on I(Na/Ca) and sarcoplasmic r...