Precise evaluation of permeability of biological tissues is often prevented by imprecise knowledge of operative forces. This problem has been approached by analysis of fluxes of isotopic species applied to opposite surfaces of a membrane. A simple and rather general flux ratio equation has been derived which may permit evaluation of membrane permeability, even without knowledge of forces, or of the nature of active transport processes. Permeability as thus defined should be insensitive to coupled flows, either of other species or of metabolism. In appropriate circumstances application of the equation may permit evaluation of the contributions of the various processes to the transport of the examined species. Composite series membranes would be expected to obey the unmodified general equation. Heterogeneous parallel pathways would alter the relation in a predictable manner. The effect of isotope interaction is specifically incorporated. The formulation is applied to consideration of energetics of active transport.
Article|
July 01 1965
Isotope Flows and Flux Ratios in Biological Membranes
Ora Kedem,
Ora Kedem
From the Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston.
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Alvin Essig
Alvin Essig
From the Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston.
Search for other works by this author on:
Ora Kedem
From the Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston.
Alvin Essig
From the Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston.
Dr. Essig's present address is the Weizmann Institute of Science, Rehovoth, Israel. After January 1, 1966, his address will be Department of Medicine, Tufts University School of Medicine, Boston
Received:
December 22 1964
Online ISSN: 1540-7748
Print ISSN: 0022-1295
Copyright © 1965 by The Rockefeller Institute Press
1965
J Gen Physiol (1965) 48 (6): 1047–1070.
Article history
Received:
December 22 1964
Citation
Ora Kedem, Alvin Essig; Isotope Flows and Flux Ratios in Biological Membranes . J Gen Physiol 1 July 1965; 48 (6): 1047–1070. doi: https://doi.org/10.1085/jgp.48.6.1047
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