AJP - Renal Physiology, Vol 234, Issue 3 182-F191, Copyright © 1978 by American Physiological Society
Factors influencing transepithelial potential difference in mammalian distal tubule
J. P. Hayslett, E. L. Boulpaep and G. H. Giebisch
Studies were performed to examine some electrical properties of the
mammalian distal tubule. Experiments were performed to evaluate the
influence of changes in ion concentration in luminal fluid on
transepithelial potential difference. Variations in the concentration of
Na+ and K+, near the physiologic range, resulted in only modest changes in
potential difference. During changes in Na+ the average slope, deltaV/ln
C2/C1, was -1.52 +/- 0.39 mV and during variations in K+ the slope was
-5.60 +/- 0.95 mV. Changes in Cl- concentration had no effect on
transepithelial potential difference. Since the sum of transferase numbers
did not equal 1, it seems likely that potential difference is influenced by
a shunt current due to cellular rheogenic pumps. These data, therefore,
indicate that variations in ion concentration in tubular fluid of the
mammalian distal tubule do not significantly influence the resting
transepithelial potential difference, and they suggest that analysis of
permselective properties of the luminal cell membrane by transepithelial
electrophysiologic approaches is probably invalid.
