| Abstrakt: |
Summary The multicompartmental frog skin epidermis model proposed in a previous paper was applied to computer simulation studies on the kinetics of the wash-out process of Na* from frog skin. Both the kinetics of loading of the model membrane with Na* from the outside to reach steady-state conditions in all internal compartments, and of the wash-out process were followed. This was done for the case when two Na+ pumps were operative, or inoperative, simulating the inhibitory effect of ouabain on active Na+ transport in frog skin. The two pumps were characterized as transmembrane Na+ flow pumps, and internal Na+ maintenance pumps which contribute but little to net inward Na+ flux. The simulation results were in good agreement, both qualitatively and quantitatively, with data in the literature on the behavior of frog skin epidermis. This analysis gives support especially to the views held by Zerahn on location and size of the active Na+ transport pool in skin epithelium. Beyond this, however, this study clearly delineates the experimental conditions under which the estimation of the Na+ transport pool by the method of measuring the wash-out rate of Na* may be successful, and under which conditions this method will fail. |
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