The sartorius muscles of 320 toads have been analyzed for Na(+) and K(+). There is a wide variation in the Na(+) content which when calculated intracellularly varied from 0 m.eq./kg. to 58 m.eq./kg. In particular it was found that the distribution of internal Na(+) in the intact animal was such that only 17 per cent of the muscles should give from the Nernst equation the observed overshoot of 3...

Electron probe x-ray microanalysis was used to measure water content and concentrations (mmol/kg dry weight) of elements (Na, P, S, Cl, K, Ca, and Mg) in myelinated axons and glial cells of rat optic nerve exposed to in vitro anoxia and reoxygenation. In response to anoxia, large, medium, and small diameter fibers exhibited an early (5 min) and progressive loss of Na and K regulation which culm...

Previous studies have shown that ischemia-reperfusion (I/R) injury is associated with cardiac dysfunction and changes in sarcolemmal Na(+)-K(+)-ATPase subunits and activity. This study was undertaken to evaluate the role of proteases in these alterations by subjecting rat hearts to different times of global ischemia, as well as reperfusion after 45 min of ischemia. Decreases in Na(+)-K(+)-ATPas...

To investigate the hypothesis that short-term submaximal training would result in changes in Na(+)-K(+)-ATPase content, activity, and isoform distribution in skeletal muscle, seven healthy, untrained men [peak aerobic power (peak oxygen consumption; Vo(2 peak)) = 45.6 ml x kg(-1) x min(-1) (SE 5.4)] cycled for 2 h/day at 60-65% Vo(2 peak) for 6 days. Muscle tissue, sampled from the vastus later...

Sickle erythrocytes (RBC) incubated under 100% nitrogen for 4 hr manifested marked Na gain with an equivalent K loss. There were no changes in cell total cation or water content under these conditions, and no irreversible sickle cells (ISC) were formed. In contrast, sickle RBC incubated for 24 hr under 100% nitrogen in a glucose-free Na medium containing calcium manifested marked ISC formation....

1. Sample from the neocortex and piriform cortex of guinea pigs and rats were incubated in inulin-containing glucose-saline. Their intracellular (non-inulin) space contained 19-27muequiv. of Na(+)/g. of original tissue. These values were stable between 30 and 100min. after incubation commenced, but addition of (22)NaCl to the neocortical samples showed them to be associated with a flux of 400mu...

Samples of external oblique muscles were surgically removed from 45 renal stone patients and analyzed for their K, Na and Mg content. The muscle samples were also measured for membrane Na, K-ATPase activity from the assay of its K+-dependent 3-0-methyl fluorescein phosphatase (K+-dependent 3-0-MFPase) activity. The results showed that the mean muscle contents +/- SEM of K, Na and Mg were 65.2 +...

Salinity stress is a brutal environmental stress which decreases the yield production of plants. Questions rise on which of the ionic stress or lack of water has deleterious effects on plants forage dry yield. Also, questions remain on whether the K+ reduction or Na+ accumulation is more important in forage dry yield reduction under salinity stress. The present experiment was conducted to answe...

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...

Changes in the number of Na+-K+-ATPase alpha-subunits, Na+-K+-ATPase activity and glycogen content of the crucian carp (Carassius carassius) brain were examined to elucidate relative roles of energy demand and supply in adaptation to seasonal anoxia. Fish were collected monthly around the year from the wild for immediate laboratory assays. Equilibrium dissociation constant and Hill coefficient ...