Effect of vasopressin on electrical resistance of renal cortical collecting tubules.

HELMAN, S. I., J. J. GRANTHAM, AND M. B. BURG. Eject of vasopressin on electrical resistance of renal cortical collecting tubules. Am. J. Physiol. 220(6) : 1825-1832. 197 1 .-A method is reported for measuring the transepithelial potential difference and electrical resistance in isolated rabbit renal cortical collecting tubules. The mean resistance with isotonic perfusion fluid was 13.8 X lo4 ohm cm (tubule length) or 867 ohm cm2 (tubule luminal area). This resistance is much higher than that previously reported for rat proximal convoluted tubules and is consistent with the much lower ionic permeability of the collecting tubule. Vasopressin caused a transient increase in potential difference (PD) without any change in electrical resistance. It is inferred that vasopressin directly increases active ion transport in the cortical collecting tubule. Increasing the tubule diameter by elevation of perfusion pressure reduced the PI> without any change in electrical resistance.