Intracellular sodium ion activity and sodium transport in rabbit urinary bladder.
1. Intracellular potentials and the intracellular activities of Na+ and K+ were examined using conventional and ion-selective micro-electrodes. 2. In animals on a normal diet, the intracellular Na+ activity was 8.6 +/- 2.9 mM (mean +/- S.D.) with a mean short-circuit current of 2.8 +/- 0.9 microA/cm2. 3. In animals on a low-Na+ diet, the intracellular Na+ activity was 18.5 +/- 9.9 mM with a short-circuit current of 4.5 +/- 1.3 microA/cm2 (mean +/- S.D.). 4. There was a correlation between short-circuit current and intracellular Na+ activity which could be fitted by a saturating hyperbolic relationship. 5. Treatment of the issue with ouabain and amiloride produced an increase and a decrease, respectively, in the intracellular Na+ activity. 6. Treatment with aldosterone produced a large increase in short-circuit current with a substantial increase in intracellular Na+ activity. 7. Intracellular Na+ activity does not seem to affect apical membrane permeability directly.
D000450:Aldosterone / Q000494:pharmacology; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002463:Cell Membrane Permeability; D066298:In Vitro Techniques; D007424:Intracellular Fluid / Q000502:physiology; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000502:physiology; D011817:Rabbits; D012964:Sodium / Q000502:physiology*; D001743:Urinary Bladder / Q000502:physiology*
D000450:Aldosterone; D010042:Ouabain; D000584:Amiloride; D012964:Sodium; D011188:Potassium