The effect of calcium withdrawal on the structure and function of the toad bladder.
Previous reports have indicated that calcium is necessary to support active sodium transport by the toad bladder, and may be required as well in the action of vasopressin on both toad bladder and frog skin. The structure and function of the toad bladder has been studied in the absence of calcium, and a reinterpretation of the previous findings now appears possible. When calcium is withdrawn from the bathing medium, epithelial cells detach from one another and eventually from their supporting tissue. The short-circuit current (the conventional means of determining active sodium transport) falls to zero, and vasopressin fails to exert its usual effect on short-circuit current and water permeability. However, employing an indirect method for the estimation of sodium transport (oxygen consumption), it is possible to show that vasopressin exerts its usual effect on Q(oo2) when sodium is present in the bathing medium. Hence, it appears that the epithelial cells maintain active sodium transport when calcium is rigorously excluded from the bathing medium, and continue to respond to vasopressin. The failure of conventional techniques to show this can be attributed to the structural alterations in the epithelial layer in the absence of calcium. These findings may provide a model for the physiologic action of calcium in epithelia such as the renal tubule.
D000818:Animals; D001001:Anura; D001693:Biological Transport, Active; D002118:Calcium / Q000494:pharmacology*; D002463:Cell Membrane Permeability; D004594:Electrophysiology; D004848:Epithelium; D066298:In Vitro Techniques; D008854:Microscopy, Electron; D010101:Oxygen Consumption; D012964:Sodium / Q000378:metabolism*; D001743:Urinary Bladder / Q000033:anatomy & histology* / Q000502:physiology*; D014667:Vasopressins / Q000494:pharmacology
D014667:Vasopressins; D012964:Sodium; D002118:Calcium
J Clin Invest. 1960 Apr;39:630-41
14419754
J Biol Chem. 1960 Jul;235:2160-3
14414942
Biol Rev Camb Philos Soc. 1962 Feb;37:82-129
13882765
Acta Physiol Scand. 1951 Aug 25;23(2-3):110-27
14868510
J Gen Physiol. 1962 May;45:921-32
14463223
J Cell Biol. 1964 Jan;20:95-111
14105220
Acta Physiol Scand. 1956 May 31;36(4):300-18
13313228
Acta Physiol Scand. 1953 Mar 31;28(1):60-76
13065150
J Cell Biol. 1963 May;17:375-412
13944428
J Biol Chem. 1959 Jun;234(6):1625-9
13654428
J Gen Physiol. 1962 May;45:905-19
13905689
J Biophys Biochem Cytol. 1958 Jul 25;4(4):475-8
13563554
J Cell Biol. 1964 Jul;22:173-88
14195608
Biochim Biophys Acta. 1961 Sep 16;52:392-5
13882706
J Gen Physiol. 1958 Mar 20;41(4):657-68
13514002
J Biophys Biochem Cytol. 1961 Aug;10:529-53
13733732