Independent stimulation of sodium entry and sodium extrusion in frog urinary bladder by aldosterone
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10−6M d-aldosterone was found to increase the sodium content in a conventional preparation (frog Ringer solution on both sides) of the urinary bladder of female frogsRana temporaria, whereas the same preparation of male frogs showed a highly significant decrease of the sodium content, which did not occur in preparations inhibited by 5·10−4M ouabain. In female frog bladders, nevertheless, the extrusion of sodium ions across the nonmucosal surfaces of epithelial cells is also stimulated by aldosterone, as shown by an increase in the transcellular sodium transport, an independent stimulation of the sodium pump by aldosterone being also involved, as demonstrated by a decrease of the sodium content in a nonpolarized preparation of female frog bladders (vesicles filled with liquid paraffin). The conclusion is drawn that aldosterone in sodium-transporting epithelial layers stimulates independently the entry of sodium ions across the mucosal membranes of the epithelial cells and their active extrusion across the nomucosal surfaces of the cells. In the nonpolarized preparation of male frog bladders no further decrease in the sodium content is observed with aldosterone, the minimum content of sodium in the transport pool being probably achieved here already by the prolonged incubation of the untreated preparation.
Key wordsFrog Bladder Sodium Transport Aldosterone Sex Dependence of Aldosterone Effect
SchlüsselwörterFroschblase Natriumtransport Aldosteron Geschlechts-abhängigkeit des Aldosteroneffekts
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