Summary
Concentration dependence of strontium (Sr) fluxes across the colon ascendens and descendens of the rat were measured in a modified Ussing-chamber. Mucosa (m) to serosa (s) and s to m Sr fluxes across both colonic segments were linearly related to the Sr concentration from 0.125 mmol/l to 10 mmol/l. In the colon ascendens m to s Sr fluxes were slightly higher than the fluxes in the opposite direction, resulting in net Sr absorption. In the colon descendens s to m fluxes were higher than the ms fluxes, resulting in net Sr secretion. Neither Sr nor calcium (Ca) showed a concentration dependent interaction with respect to their unidirectional fluxes in both parts of the colon. Only in the colon ascendens Sr at the highest concentration (10 mmol/l) inhibited m to s calcium transport.
Experiments, in which the voltage dependence of the unidirectional Sr fluxes was measured confirmed the results obtained from the concentration dependence: (1) The unidirectional fluxes of Sr across the colon ascendens and descendens were totally voltage dependent, i.e. diffusive. (2) In the colon descendens the voltage dependence of the s to m flux was steeper than the flux from m to s. It is hypothesized that this prevalence is caused by an anomalous solvent drag effect. 1.25-Dihydroxyvitamin D3 [1.25 (OH)2D3] stimulated m to s calcium flux in the colon descendens but had no effect on Sr flux.
The results demonstrate that Sr and Ca in the rat colon are transported by different mechanisms. In contrast to the Ca transport the Sr flux is only diffusive and insensitive to 1.25 (OH)2D3.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Duggleby RG (1984) Regression analysis of nonlinear Arrhenius plots: an empirical model and a computer program. Comp Biol Med 14:447–455
Dumont PA, Curran PF, Solomon AK (1960) Calcium and strontium in rat small intestine. Their fluxes and their effect on Na flux. J Gen Physiol 43:1119–1136
Favus MJ, Kathpalia SC, Coe FL, Mond AE (1980) Effects of diet calcium and 1.25-dihydroxyvitamin D3 on colon active calcium transport. Am J Physiol 238:G75-G78
Favus MJ, Kathpalia SC, Coe FL (1981) Kinetic characteristics of calcium absorption and secretion by rat colon. Am J Physiol 240:G350-G354
Favus MJ, Langman CB (1984) Effects of 1.25-dihydroxyvitamin D3 on colonic calcium transport on vitamin D-deficient and normal rats. Am J Physiol 246:G268-G273
Frizzell RA, Schultz SG (1972) Ionic conductances of extracellular shunt pathway in rabbit ileum. J Gen Physiol 59:318–346
Harrison HC, Harrison HE (1969) Calcium transport by rat colon in vitro. Am J Physiol 217:121–125
Hendrix JZ, Alcock NW, Archibald RM (1963) Competition between calcium, strontium and magnesium for absorption in the isolated rat intestine. Clin Chem 9:734–744
Karbach U, Rummel W (1984) Wirkung von 1,25-Vitamin D3 auf den Kalziumtransport am Colon ascendens und Colon descendens der Ratte. Verh Dt Ges Inn Med 90:1631–1634
Karbach U, Bridges RJ, Rummel W (1984) Segmental heterogeneity of calcium transport at rat colon. Gastroenterol Clin Biol 8:867 (Abstr)
Karbach U, Bridges RJ, Rummel W (1985) The role of the paracellular pathway in the net transport of calcium across the colonic mucosa. Naunyn-Schmiedeberg's Arch Pharmacol 334:525–530
Karbach U, Ewe K (1985) Calcium and magnesium transport and the influence of 1.25-dihydroxyvitamin D3. In vitro perfusion study at the colon of the rat. Gut (in review)
Kimberg D, Schachter D, Schenker H (1961) Active transport of calcium by intestine: effects of dietary calcium. Am J Physiol 200:1256–1262
Lee DBN, Walling MW, Gafter U, Silis V, Coburn JW (1980) Calcium and inorganic phosphate transport in rat colon. J Clin Invest 65:1326–1331
Mraz FR, Bacon JA (1960) Influence of excessive amounts of vitamin D3 on strontium-89 metabolism in the rat. Proc Soc Exp Biol Med 104:1–3
Petith MM, Schedl HP (1976) Intestinal adaptation to dietary calcium restriction: in vivo cecal and colonic calcium transport in the rat. Gastroenterology 71:1039–1042
Petith MM, Wilson HD, Schedl HP (1979) Vitamin D dependence of in vivo calcium transport and mucosal calcium binding protein in rat large intestine. Gastroenterology 76:99–104
Schachter D, Kimberg DV, Schenker H (1961) Active transport of calcium by intestine: action and bio-assay of vitamin D. Am J Physiol 200:1263–1271
Schultz SG, Zalusky R (1964) Ion transport in isolated rabbit ileum. I. Short-circuit current and Na fluxes. J Gen Physiol 47:567–584
Ussing HH, Johansen B (1969) Anomalous transport of sucrose and urea in toad skin. Nephronology 6:317–328
Walling MW, Kimberg DV (1973) Active secretion of calcium by adult rat ileum and jejunum in vitro. Am J Physiol 225:415–422
Wasserman RH (1960) Metabolic basis of calcium and strontium discrimination: Studies with surviving intestinal segments. Proc Soc Exp Biol Med 104:92–95
Wasserman RH (1963) Vitamin D and the absorption of calcium and strontium in vivo. In: Wasserman RH (ed) The transfer of calcium and strontium across biological membranes. Academic Press, New York, pp 211–228
Author information
Authors and Affiliations
Additional information
Supported by the Deutsche Forschungsgemeinschaft SFB 38 “Membranforschung”
Send offprint requests to U. Karbach at the above address
Rights and permissions
About this article
Cite this article
Karbach, U., Rummel, W. Strontium transport in the rat colon. Naunyn-Schmiedeberg's Arch Pharmacol 335, 91–96 (1987). https://doi.org/10.1007/BF00165042
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00165042