Fluidity-induced changes in diffusion through membranes: a predictive model
Abstract
Diffusion of uncharged solutes through a neutral monolayer is limited by the probability of sufficiently sized vacancies forming randomly between membrane barriers. If the one-dimensional distribution of barriers is described by the Gaussian, a change in membrane fluidity can be represented by a change in variance of the distribution. By the reproductive property of Gaussian distributions, the vacancy size would also be altered.
The effect of this change on the probability of solute passage is dependent on the ratio between solute size (V i) and mean vacancy size \overlineV . An increase in fluidity may hamper diffusion of a solute if V i < \overlineV, whereas a fluidity decrease would augment diffusion. For V i> \overlineV, a fluidity change would have the opposite effect. If V i ⪡, =, or ⪢ \overlineV, no effect would obtain. There are, then, critical values for V i / \overlineV . The influence of temperature on conduction velocity in squid axons illustrates how this model could affect physiological systems.- Publication:
-
Journal of Theoretical Biology
- Pub Date:
- 1977
- DOI:
- 10.1016/0022-5193(77)90166-7
- Bibcode:
- 1977JThBi..68..293C