Correlation between [formula omitted] ATPase activities and the rate of isotonic fluid transport of gallbladder epithelium

Abstract

1. 1. Relative and absolute ATPase activities have been determined in rabbit and guinea pig whole gallbladder homogenates. 2. 2. Absolute (Na + − K +)-ATPase activities were correlated with the rate of fluid transport in both species. The ratio of equiv Na + transported per mole ATP was 1.4 and 2.0 in rabbit and guinea pig, respectively. 3. 3. Variation in fluid transport of individual gallbladders ( 40–140 μ l H 2 O· h −1 cm −2 ) could be directly correlated with (Na +−K +)-ATPase activity. 4. 4. Stimulation of the (Na +−K +)-ATPase system by 10 −9 M ouabain and 1.5 mM K + in rabbit gallbladder also increased the rate of fluid transport. 5. 5. These results indicate that the (Na +−K +)-ATPase system plays the primary role in transcellular isotonic fluid transport in gallbladder despite the absence of a secretory potential.