Cation exchange binding of rubidium and cesium by rat liver cell microsomes

✍ Scribed by Hisashi Sanui

• Publisher: John Wiley and Sons
• Year: 1971
• Tongue: English
• Weight: 406 KB
• Volume: 78
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/jcp.1040780306

✦ Synopsis

The rubidium and cesium binding characteristics of rat liver cell microsomes were studied by a n equilibration, centrifugation and washing procedure. Concentration dependence experiments, in which microsomes were equilibrated i n media containing 0 to 400 mM rubidium or cesium chloride at pH 6.9, yielded saturation type adsorption isotherms similar to those previously reported for sodium and potassium. Mass law analysis of the data yielded apparent dissociation constants of 21 X 10-3 eq/liter and 19 X 10-3 eq/liter for rubidium and cesium binding, respectively. The results indicate that cesium is bound slightly more strongly than rubidium, and that both these cations may be bound more strongly than sodium or potassium. The maximum binding capacity at pH 6.9 was approximately 1.3 meq rubidium or cesiumlg nitrogen. Sodium, potassium, magnesium and calcium generally associated with the isolated microsomes decreased concomitantly with increasing bound rubidium or cesium, demonstrating the ion exchange nature of the binding. Results of pH-dependence experiments showed that following equilibration of the microsomes i n media containing approximately 96 mM rubidium or cesium a t various pH values, bound rubidium or cesium was essentially zero at pH less than five, increased sharply between pH 5 and 7, and tended to level off at higher pH. The present results further characterize the cation binding properties of the microsomal material.