The Effect of Diuretics and Lithium on ³H‐Ouabain Binding Site Concentration and Na,K‐Content in Rat Skeletal Muscle

Abstract: Previous studies have shown an increase in ³H‐ouabain binding sites or Na,K‐pumps in vitro in cultured cells in response to incubation in low K, diuretics or lithium. However, in the present study the administration in vivo of various diuretics or lithium combined with supplementary K was not associated with any significant changes in Na,K‐content or ³H‐ouabain binding site concentration in rat skeletal muscle. When the diuretics were administered in combination with only the basal K requirement a decrease in both K‐content and ³H‐ouabain binding site concentration was seen. This indicates that the decrease in ³H‐ouabain binding site concentration is not caused by these drugs per se but is secondary to the associated K‐depletion. The discrepancy between the results obtained using isolated cells and rat skeletal muscles could be related to the fact that cultured cells are not subject to the normal growth control of the intact organism. It should be emphasized that results obtained using cultured cells do not necessarily reflect processes taking place in the intact organism. 1986 Nordic Pharmacological Society