Effects of amiloride on active sodium transport by the isolated frog skin: evidence concerning site of action

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Summary

  • 1Amiloride reduces short-circuit current and potential difference across the isolated frog skin.
  • 2Isotopically measured sodium influx and efflux are diminished.
  • 3Total electrical conductance and partial sodium conductance are diminished, the reduction in total conductance being entirely accounted for by the reduction in partial sodium conductance.
  • 4The effect of antidiuretic hormone (ADH), cyclic 3′5′-adenosine monophosphate (cyclic AMP) and theophylline can be antagonized by pretreatment with amiloride but the antagonism can be abolished by increasing the concentration of these compounds.
  • 5Amiloride has no effect on oxygen consumption in concentrations which inhibit sodium transport. However, it prevents the stimulatory effect of ADH on oxygen consumption.
  • 6The results are consistent with an action of amiloride at the passive outside membrane of the transporting cells of isolated frog skin.

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