Competitive membrane adsorption of Na, K, and Ca in smooth muscle cells.

Autor: Kolber, Michael, Breemen, Cornelis
Zdroj: Journal of Membrane Biology; 1981, Vol. 58 Issue 2, p115-121, 7p
Abstrakt: A theory for Na, K and Ca competitive adsorption to a charged membrane is used to explain a number of experimental observations in smooth muscle. Adsorption is described by Langmuir isotherms for mono- and divalent cations which in turn are coupled in a self-consistent way to the bulk solution through the diffuse double layer theory and the Boltzman equations. We found that the dissociation constants for binding of Na, K and Ca in guinea pig taenia coli are ca. 0.009, 1.0, and 4×10 m, respectively. Furthermore, the effect of a Ca pump that maintains free surface Ca concentration constant is investigated. A decrease in intracellular Na content results in an increased Ca uptake; part of this uptake is due to an increase in surface-bound Ca in an intracellular compartment which is in contact with the myofilaments. Variations in the amount of charge available to bind Ca and the surface charge density are studied and their effect interpreted in terms of different pharmacological agents. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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