Determination of Urea Permeability in Red Cells by Minimum Method
| Autor: | R. I. Sha'afi, G. T. Rich, A. K. Solomon, D. C. Mikulecky |
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| Jazyk: | angličtina |
| Rok vydání: | 1970 |
| Předmět: |
Cell Membrane Permeability
Erythrocytes Physiology Chemistry Diffusion Osmolar Concentration Thermodynamics Models Theoretical Omega Article Volumetric flow rate Membrane Volume (thermodynamics) Hematocrit Permeability (electromagnetism) Osmotic Pressure Methods Osmotic pressure Urea Restrictive Barrier |
| Zdroj: | The Journal of General Physiology |
| ISSN: | 1540-7748 0022-1295 |
| Popis: | A new method has been developed for measuring the permeability coefficient, ω, of small nonelectrolytes. The method depends upon a mathematical analysis of the time course of cell volume changes in the neighborhood of the minimum volume following addition of a permeating solute to an isosmolal buffer. Coefficients determined by the minimum volume method agree with those obtained using radioactive tracers. ω for urea in human red cells was found to decrease as the volume flow, Jv, into the cell increased. Such behavior is entirely unexpected for a single uniform rate-limiting barrier on the basis of the linear phenomenological equations derived from irreversible thermodynamics. However, the present findings are consonant with a complex membrane system consisting of a tight barrier on the outer face of the human red cell membrane and a somewhat less restrictive barrier behind it closer to the inner membrane face. A theoretical analysis of such a series model has been made which makes predictions consistent with the experimental findings. |
| Databáze: | OpenAIRE |
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