Summary
The main duct of the rat submaxillary gland has been isolated and perfusedin vitro while incubated in a plasma bath. It reabsorbs Na and secretes K and HCO3 at rates comparable to those reported for the ductin vivo and develops a transepithelial potential difference with magnitude dependent on the luminal Na concentration.
The kinetics of ductal Na transport were studied by varying the Na concentration in the plasma bath step-wise from 149 to 320 mM and then the Na concentration in the luminal perfusate so as to produce zero nett flux of Na and water between lumen and bath. It was found that active Na transport by the duct showed saturation kinetics with a half-saturation constant of about 29 mM. The saturation curve could not be described in terms of a single Michaelis-Menten hyperbola although a more complex expression consisting of two such hyperbolic transport terms could easily be fitted to the data.
Utilizing published values for unidirectional Na flux ratios it was calculated that the active Na transport rate when the luminal fluid had a plasma-like Na concentration was 4.37×10−9 mol·cm−2·s−1 and the epithelial Na permeability coefficient was 5.27×10−6cm·s−1.
Although the kinetics of K and HCO3 secretion were not studied in detail it was observed incidentally that ductal secretion of these two ions still persisted even when their luminal concentrations were raised, respectively, to 197–225 mM and 80–120 mM.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Cereijido, M., Herrera, F. C., Flanigan, W. J., Curran, P. F.: The influence of Na concentration of Na transport across frog skin. J. gen. Physiol.47, 879 to 893 (1964)
Curran, P. F., Solomon, A. K.: Ion and water fluxes in the ileum of rats. J. gen. Physiol.41, 143–168 (1957)
Diamond, J. M.: The reabsorptive function of the gall-bladder. J. Physiol. (Lond.)161, 442–473 (1962)
Endre, Z. H.: A micropuncture and microperfusion investigation of electrolyte transport in the rabbit submaxillary gland. Honours Thesis at the University of Sydney, 1972
Field, M. J., Young, J. A.: Sodium and potassium transport in the rat submaxillary main duct perfused in vitro. Proc. Aust. Physiol. Pharmacol. Soc.3, No. 2, 159 (1972)
Györy, A. Z., Lingard, J. M., Young, J. A.: Kinetics of Na+ reabsorption in rat proximal tubules perfusedin vivo. Proc. Aust. Physiol. Pharmacol. Soc.4, 52–53 (1973)
Hodgkin, A. L., Katz, B.: The effect of sodium ions on the electrical activity of the giant axon of the squid. J. Physiol. (Lond.)108, 37–77 (1943)
Knauf, H.: The isolated salivary duct as a model for electrolyte transport studies. Pflügers Arch.333, 82–94 (1972)
Knauf, H., Frömter, E.: Die Kationenausscheidung der großen Speicheldrüsen des Menschen. Pflügers Arch.316, 213–237 (1970)
Kokko, J. P.: Sodium. chloride and water transport in the descending limb of Henle. J. clin. Invest.49, 1838–1846 (1970)
Leaf, A.: Transepithelial transport and its hormonal control in toad bladder. Ergebn. Physiol.56, 216–263 (1965)
Martin, C. J., Frömter, E., Gebler, B., Knauf, H., Young, J. A.: The effects of carbachol on water and electrolyte fluxes and transepithelial potential differences of the rabbit submaxillary main duct perfusedin vitro. Pflügers Arch.341, 131–142 (1973)
Morgan, T., Berliner, R. W.: Permeability of the loop of Henle, vasa recta, and collecting ducts to water, urea and sodium. Amer. J. Physiol.215, 108–115 (1968)
Neame, K. D., Richards, T. G.: Elementary kinetics of membrane carrier transport. Oxford: Blackwells 1972
Riggs, D. S.: The mathematical approach to physiological problems, pp. 276–280. Cambridge (U.S.A.): M.I.T. Press 1970
Robinson, R. A., Stokes, R. H.: Electrolyte solutions, 2nd rev. ed. London: Butterworths 1965
Schneyer, L. H.: Secretion of potassium by perfused excretory duct of rat submaxillary gland. Amer. J. Physiol.217, 1324–1329 (1969)
Schneyer, L. H., Young, J. A., Schneyer, C. A.: Salivary secretion of electrolytes. Physiol. Rev.52, 720–777 (1972)
Stein, W. D.: The movement of molecules across cell membranes. New York-London: Academic Press 1967
Ullrich, K. J.: Handbook of Physiology, Section 8 (with mathematical appendix by F. Sauer). Washington: American Physiological Society 1973 (in press)
Young, J. A.: Microperfusion investigation of chloride fluxes across the epithelium of the main excretory duct of the rat submaxillary gland. Pflügers Arch.303, 366–374 (1968)
Young, J. A., Frömter, E., Schögel, E., Hamann, K. F.: A microperfusion investigation of sodium resorption and potassium secretion by the main excretory duct of the rat submaxillary gland. Pflügers Arch. ges. Physiol.295, 157–172 (1967)
Young, J. A., Martin, C. J.: The effect of a sympatho-and a parasympatho mimetic drug on the electrolyte concentrations of primary and final saliva of the rat submaxillary gland. Pflügers Arch.327, 285–302 (1971)
Young, J. A., Martin, J. C., Asz, M., Weber, F. D.: A microperfusion investigation of bicarbonate secretion by the rat submaxillary gland. The action of a parasympathomimetic drug on electrolyte transport. Pflügers Arch.319, 185–199 (1970)
Young, J. A., Schögel, E.: Micropuncture investigation of sodium and potassium excretion in rat submaxillary saliva. Pflügers Arch. ges. Physiol.291, 85–98 (1966)
Young, J. A., Shagrin, J. M.: Nanolitre micromethods in biological research: determination of sodium, potassium and melting point. Proc. Aust. Ass. clin. Biochem.1, 333–336 (1968)
Author information
Authors and Affiliations
Additional information
A preliminary report of this work was presented to a meeting of the Australian Physiological and Pharmacological Society and a Regional Meeting of the International Union of Physiological Sciences held at Sydney University in August 1972 [5].
Rights and permissions
About this article
Cite this article
Field, M.J., Young, J.A. Kinetics of Na transport in the rat submaxillary main duct perfusedin vitro . Pflugers Arch. 345, 207–220 (1973). https://doi.org/10.1007/BF00586335
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00586335