Summary
The exchangeability of toad bladder epithelial cell potassium has been investigated. An insignificant amount of cellular potassium exchanged with mucosal medium42K. From the rate of uptake of42K into the cells from the serosal medium at least two cellular potassium pools were identified. The more rapidly exchanging pool contained about one-quarter to one-third of the cellular potassium and exchanged with a half-time of about 30 min. It was from this pool that potassium was lost from cells exposed to ouabain or to a potassium-free medium. In addition, when 3.5mm rubidium replaced 3.5mm potassium in sodium Ringer's the epithelial cells lost in 60 min about one-quarter of their cellular potassium in exchange for rubidium. Inhibition of transepithelial sodium transport by amiloride, 10−5 mm, seemed to depress the rate of potassium uptake into the more rapidly exchanging pool without affecting total cellular potassium content. However, stimulation of transepithelial sodium transport by vasopressin appeared not to affect the rate of potassium uptake. The rate of potassium uptake into this pool seemed much less than that required for a tight 1∶1 coupling between transepithelial sodium transport and potassium uptake. The remaining cellular potassium exchanged at a much slower rate and even after 19 hours of incubation only 67% of cellular potassium was labelled. If this slower exchanging potassium represents a single pool, 99% of cellular potassium would be labelled only after incubation with42K for 56 hours.
Similar content being viewed by others
References
Bentley, P.J. 1960. The effect of vasopressin on the SCC across the wall of the isolated bladder of the toadBufo marinus.J. Endocrinol. 21:161
Bentley, P.J. 1968. Amiloride: A potent inhibitor of Na transport across the toad bladder.J. Physiol. 195:317
Biber, T.U.L., Aceves, J., Mandel, L.J. 1972. Potassium uptake across serosal surface of isolated frog skin epithelium.Am. J. Physiol. 222:1366
Davies, H.E.F., Martin, D.G., Sharp, G.W.G. 1968. Differences in the physiological characteristics of bladders of toads from different geographical sources.Biochim. Biophys. Acta 150:315
Essig, A., Leaf, A. 1963. The role of potassium in active transport of sodium by the toad bladder.J. Gen. Physiol. 46:505
Finn, A.L. 1973. Ouabain-dependent potassium-potassium exchange in the toad bladder.J. Membrane Biol. 12:301
Finn, A.L. 1974. Transepithelial potential difference in toad urinary bladder is not due to ionic diffusion.Nature 250:495
Finn, A.L., Nellans, H. 1972. The kinetics and distribution of potassium in the toad bladder.J. Membrane Biol. 8:189
Frazier, H.S., Leaf, A. 1963. The electrical characteristics of active sodium transport in the toad bladder.J. Gen. Physiol. 46:491
Gatzy, J.T. 1971. The effect of potassium-sparing diuretics on ion transport across the excised toad bladder.J. Pharmacol. Exp. Ther. 176:580
Gatzy, J.T., Clarkson, T.W. 1965. The effect of mucosal and serosal solution cations on bioelectric properties of the isolated toad bladder.J. Gen. Physiol. 48:647
Handler, J.S., Preston, A.S., Orloff, J. 1972. Effect of ADH, aldosterone, ouabain, and amiloride on toad bladder epithelial cells.Am. J. Physiol. 222:1071
Hays, R.M., Leaf, A. 1961. The problem of clinical vasopressin resistance: In vitro studies.Ann. Intern. Med. 54:700
Herrera, F.C. 1966. Action of ouabain on sodium transport in the toad urinary bladder.Am. J. Physiol. 210:980
Kallus, F.T., Vanatta, J.C. 1970. The bladder ofBufo marinus as an excretory organ for potassium.Tex. Rep. Biol. Med. 27:419
Koefoed-Johnsen, V., Ussing, H.H. 1958. The nature of the frog skin potential.Acta Physiol. Scand. 42:298
Leb, D.E., Hoshiko, T., Lindley, B.D. 1965. Effects of alkali metal cations on the potential across toad and bullfrog urinary bladder.J. Gen. Physiol. 48:527
Lipton, P., Edelman, I.S. 1971. Effects of aldosterone and vasopressin on electrolytes of toad bladder epithelial cells.Am. J. Physiol. 221:733
Macknight, A.D.C., Civan, M.M., Leaf, A. 1975a. The sodium transport pool in toad urinary bladder epithelial cells.J. Membrane Biol. 20:365
Macknight, A.D.C., Civan, M.M., Leaf, A. 1975b. Some effects of ouabain on cellular ions and water in epithelial cells of toad urinary bladder.J. Membrane Biol. 20:387
Macknight, A.D.C., DiBona, D.R., Leaf, A., Civan, M.M. 1971. Measurement of the composition of epithelial cells from the toad urinary bladder.J. Membrane Biol. 6:108
Macknight, A.D.C., Leaf, A., Civan, M.M. 1971. Effects of vasopressin on the water and ionic composition of toad bladder epithelial cells.J. Membrane Biol. 6:127
Mendoza, S.A. 1972. Potassium dependence of base-line and ADH-stimulated sodium transport in toad bladder.Am. J. Physiol. 233:120
Robinson, B.A., Macknight, A.D.C. 1976a. Relationships between serosal medium potassium concentration and sodium transport in toad urinary bladder. I. Effects of different medium potassium concentrations on electrical parameters.J. Membrane Biol. 26:217
Robinson, B.A., Macknight, A.D.C. 1976b. Relationships between serosal medium potassium concentration and sodium transport in toad urinary bladder. II. Effects of different medium potassium concentrations on epithelial cell composition.J. Membrane Biol. 26:239
Skou, J.C. 1965. Enzymatic basis for active transport of Na+ and K+ across cell membrane.Physiol. Rev. 45:596
Ussing, H.H., Erlij, D., Lassen, U. 1974. Transport pathways in biological membranes.Annu. Rev. Physiol. 36:17
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Robinson, B.A., Macknight, A.D.C. Relationships between serosal medium potassium concentration and sodium transport in toad urinary bladder. J. Membrain Biol. 26, 269–286 (1976). https://doi.org/10.1007/BF01868877
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF01868877