Kedem O, Essig A
J Gen Physiol. 1965 Jul;48(6):1047-70. doi: 10.1085/jgp.48.6.1047.
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.
生物组织渗透性的精确评估常常因对作用力的了解不准确而受到阻碍。这个问题已通过分析施加于膜相对表面的同位素物质通量来解决。已经推导出一个简单且相当通用的通量比方程，该方程或许能够评估膜的渗透性，即便不知道作用力或主动运输过程的性质。如此定义的渗透性应不受其他物质或代谢的耦合流影响。在适当情况下，应用该方程或许能够评估各种过程对所研究物质运输的贡献。复合串联膜预计会遵循未修正的通用方程。异质平行途径会以可预测的方式改变这种关系。具体纳入了同位素相互作用的影响。该公式被应用于主动运输能量学的考量。
