We studied the pathways for HCO-3 transport in basolateral membrane vesicles (BLMV) purified from rat medullary thick ascending limbs (MTAL). An inward HCO-3 gradient in the presence of an inside-positive potential stimulated the rate of 22Na uptake minimally and did not induce a 22Na overshoot, arguing against the presence of electrogenic Na+-HCO-3 cotransport in these membranes. An inside-aci...

Secretory vesicles of sympathetic neurons and chromaffin granules maintain a pH gradient towards the cytosol (5.5 vs. 7.2) promoted by the V-ATPase activity. This gradient of pH is mainly responsible for the accumulation of amines. The secretory vesicles contain large amounts of total Ca(2+), but the free intragranular [Ca(2+)], the mechanisms for Ca(2+) uptake and release from the granules and...

INTRODUCTION This prospective non-interventional study intended to assess the prognostic value of gastric intramucosal acidosis in patients with severe trauma admitted to a medical/surgical ICU. METHODS Gastric tonometer catheters were introduced to measure air PCO2 level (Tonocap device) in forty consecutive critically ill trauma patients. Gastric intramucosal pH, air PCO2 gradient, lactate ...

Acidification of the luminal solution by the isolated turtle bladder involves H(+) secretion by a pump at the luminal membrane. The OH(-) dissociated in this process reacts with CO(2) and forms HCO(3) (-) which moves passively out of the cell across the serosal cell membrane. In the present study, this exit step for HCO(3) (-) was inhibited by serosal addition of the disulfonic stilbene, SITS, ...