Evidence for @entity8108 secretion by the in vivo XXXX gallbladder.

@entity1 @entity7362 @entity4024 @entity235 @entity840 @entity95 @entity1372 @entity3158 @entity5990 @entity6741 @entity544 @entity460 @entity8108 @entity16415 @entity14764
In @entity1 and most other species, a decline in pH of gallbladder contents occurs during the concentration of bile. Recent in vitro studies in @entity95 , @entity840 , and Necturus gallbladders have strongly suggested mucosal @entity8108 secretion during @entity1372 reabsorption, presumably representing a @entity4024 / @entity8108 exchange. The present in vivo studies are the first attempt to determine whether @entity8108 secretion by the gallbladder can be demonstrated in the living animal. Gallbladder bile was obtained from 27 anesthetized @entity235 after 12-24-h fasts; 12 samples of common duct bile were also obtained in 3 @entity235 during variable @entity7362 infusion. In common duct bile, observed ranges were as follows: pH, 7.37-7.85; @entity3158 partial pressure (PCO2), 21-32 mmHg; total @entity3158 concentration ([TCO2]), 16.4-41.4 mM; total @entity6741 concentration ([ @entity14764 ]), 16-93 mM; and [ @entity4024 ], 153-192 mM. In gallbladder bile, respective ranges were as follows: pH, 5.72-7.29; PCO2, 36-101 mmHg; [TCO2], 1.21-15.5 mM; [ @entity14764 ], 150-305 mM; and [ @entity4024 ], 199-266 mM. In all samples [ @entity4024 ] was linearly related to [ @entity14764 ]. @entity544 partial pressure increased from a mean of 27.3 mmHg in common duct bile to greater than 100 mmHg in gallbladder bile at [ @entity14764 ] = 180 mM, then declined to approximately 36 mmHg as [ @entity14764 ] increased to greater than 300 mM. Peak PCO2 occurred at pH approximately 6.4-6.6, then declined as pH decreased to approximately 5.7. Bile to plasma PCO2 ratios increased from a mean of 1.08 in common duct samples to greater than 2.0 in gallbladder samples at pH approximately 6.3, then declined to approximately 1.0 in fully concentrated bile. If the high PCO2 values in bile were solely due to tissue @entity3158 production, a sustained increase in PCO2 throughout @entity4024 + reabsorption might be expected. The results strongly suggest @entity8108 secretion (HCO3- neutralization), as peak PCO2 occurred when [ @entity14764 ] was only about 180 mM, long before @entity1372 absorption was complete. It is hypothesized that @entity8108 secretion may have important favorable effects on @entity460 lithogenicity, reducing the likelihood of the formation of @entity16415 - containing @entity5990 .
