The aim of this study was to evaluate the role of the kidney in mediating the signals involved in adaptive changes in luminal Na+/H+ exchange and basolateral Na+:HCOcotransport systems in metabolic acidosis. Proximal tubular suspensions were prepared from rabbit kidney cortex and incubated in acidic (A) or control (C) media (pH 6.9 vs 7.4, 5% C02) for 2 h. Brush border membrane (BBM) and basola...

Voltage-sensitive Na channels were studied in cultures of neonatal rat cortical astrocytes. These channels were present at all times in culture as determined by tracer 22Na+ influx in the presence of batrachotoxin (BTX) and sea anemone polypeptide toxin (AxTx). The affinity of saxitoxin (STX) binding and sensitivity to STX inhibition of sodium influx were utilized to characterize these channels...

We previously reported that inappropriate renal vasoconstriction in Dahl salt-sensitive (DS) rats fed high NaCl diets may cause sodium retention. The present study examined the distribution and elimination of 22Na in DS and Dahl salt-resistant (DR) rats, and we determined whether an abnormality in renal function might also cause sodium retention in DS rats. Following an intravenous bolus of 4 m...

Purified canine cardiac sarcolemmal membrane vesicles exhibit a sodium ion for proton exchange activity (Na+/H+ exchange). Na+/H+ exchange was demonstrated both by measuring rapid 22Na uptake into sarcolemmal vesicles in response to a transmembrane H+ gradient and by following H+ transport in response to a transmembrane Na+ gradient with use of the probe acridine orange. Maximal 22Na uptake int...

The effects of insulin and ouabain on 22Na efflux and net Na loss were examined in frog sartorius muscles. After removal of ouabain, 22Na efflux which had been inhibited by ouabain remained at the inhibited level for more than 2 hr. In ouabain-free solution, insulin stimulated the Na efflux from ouabain-preincubated muscles. The stimulating effect of insulin on 22Na efflux was completely blocke...

We have investigated the effect of antibodies from a myasthenic serum on the physiological properties of acetylcholine receptors (AChRs) in myotubes of a mouse muscle cell line, C2. The antibodies in this serum blocked the binding of 125I-alpha-bungarotoxin to the myotubes to an extent of about 50%. The antibodies also inhibited the increase in 22Na influx caused by carbamylcholine (CARB). At a...

In vitro evidence suggests that intraluminal nucleotides, acting on apical P2 receptors, may influence amiloride-sensitive sodium reabsorption in collecting ducts. The present study has assessed this possibility directly in anesthetized rats, by determining the urinary recovery of 22Na relative to that of [14C]inulin (Na/inulin recovery ratio) during in vivo microperfusion of late distal tubule...