This study sought to characterize the mechanism of Na transport across basolateral membrane vesicles of rat distal colon. Both an outward proton gradient and an inward bicarbonate gradient stimulated 22Na uptake. Proton gradient-stimulated 22Na uptake was activated severalfold by the additional presence of an inward bicarbonate gradient, and bicarbonate gradient-stimulated 22Na uptake was signi...

1. Whole-body elimination rate of 22Na+ was decreased in normotensive or borderline first-degree relatives of hypertensive probands. 2. Whole-body potassium, exchangeable sodium and urine excretion of sodium, potassium and creatinine were similar in relatives and controls. 3. Erythrocyte net influx of 22Na+ was significantly increased in normotensive relatives. 4. Abnormal whole-body and cellul...

Brain capillary endothelial cells form a blood-brain barrier (BBB) that appears to play a role in fluid and ion homeostasis in brain. One important transport system that may be involved in this regulatory function is the Na+, K+-ATPase that was previously demonstrated to be present in isolated brain capillaries. The goal of the present study was to identify additional Na+ transport systems in b...

Acute subcutaneous (s.c.) administration of aldosterone increases ex vivo 22Na efflux from rat tail artery smooth muscle, which appears to be due to a specific action on mineralocorticoid receptors. Indeed, this effect is blocked by the antimineralocorticoid compounds RU 28318 [17 beta-hydroxy-3-oxo,7 alpha-propyl(17 alpha)-pregn 4-ene, 21 potassium carboxylate] and spironolactone. The specific...

In this study we have found that L-glutamic acid, as well as being taken up by a Na+-dependent mechanism, will stimulate the uptake of 22Na+ by primary astrocyte cultures from rat brain in the presence of ouabain. By simultaneously measuring the uptake of 22Na+ and L-3H-glutamate a stoichiometry of 2-3 Na+ per glutamate was measured, implying electrogenic uptake. Increasing the medium K+ concen...

Ouabain-sensitive 22Na efflux from right-side-out membrane vesicles prepared from dog kidney has been examined with a time resolution of 30 msec. The vesicles are preloaded with 22Na and caged ATP [P3-1-(2-nitro)phenylethyl adenosine triphosphate], so that transport by the Na pump can be initiated by light. After a brief illumination, which releases less ATP than the number of catalytic sites, ...

2014 We measured the cross sections of 22Na, 20,21,22Ne and 36,38,39,42Ar in nuclear reactions induced by the proton bombardment of Mg, Al, Si, Ca and Fe at several energies between 0.059 and 24 GeV using highsensitivy mass-spectrometry for noble gases and 03B3-counting for 22Na. We then evaluated the cross section ratio versus energy for the 22Na/22Ne, 26Al/21Ne, 39Ar/38Ar and 36Cl/36Ar radioa...

Abnormal erythrocyte Na+ transport has been reported in patients with essential hypertension and some first-degree relatives. The two major techniques now employed for estimating Na+ transport--Na+/Li+ countertransport and Na+/K+ cotransport--are rather intricate and time consuming. Furthermore, the precise nature of the transport processes being measured is not clear. We have developed a simpl...

The efflux of 22Na from vesicles formed by axolemma fragments isolated from lobster nerves was studied in the presence and in the absence of drugs having well-known action on the sodium channels. The vesicles were equilibrated 12-14 h at 4 degrees C with 22Na in lobster solution containing 1 mM ouabain. Afterwards the suspension was divided: one portion was used as control and the others were t...

We discuss the suitability of some radioactive isotopes as volume markers in radioimmunoassays, from a radiochemical point of view. For three eligible isotopes (22Na, 60Co, and 75Se) we studied the concentration of the marker in the precipitate formed in the separation phase of radioimmunoassays. For all those kinds of separations tested (charcoal, ammonium sulfate, polyethylene glycol, and eth...