Salivary secretion in the rat after ouabain

Abstract

Ouabain was injected intravenously (0.5 mg/kg) or intraperitoneally into anesthetized rats. After 50 min, pilocarpine was administered and saliva was collected from submaxillary or parotid glands. [K] was found to be elevated in both secretions, while [Na] was reduced in parotid saliva. Changes in salivary flow were not the major cause of the alterations in electrolytes. Analyses of gland tissues after injection of ouabain showed [K] and [Na] to be essentially unaffected in whole tissue or cell water. Blood flow to the glands also was apparently unchanged. However, with incubated submaxillary slices, 5 x 10^–4 m ouabain inhibited accumulation of K, and this inhibition could be prevented by raising [K] in the incubation medium. These effects were evaluated in relation to the current concept that salivary K is derived largely from intracellular stores of the ion, with ensuing secondary equilibration. It was concluded that the effects of ouabain are consistent with this model, and that, in vivo, ouabain probably inhibited reabsorption of K after its initial release from secretory cells.