Urinary acidification: CO2 transport by the rabbit proximal straight tubule

DG Warnock, MB Burg - American Journal of Physiology …, 1977 - journals.physiology.org
DG Warnock, MB Burg
American Journal of Physiology-Renal Physiology, 1977journals.physiology.org
Proximal straight tubules from rabbit kidneys were perfused in vitro in order to study
transport of bicarbonate. Total CO2 content was measured in perfused and collected tubule
fluid, using microcalorimetry. When the initial perfusate and bath contained 25 mM
bicarbonate, the concentration of total CO2 decreased in the collected tubule fluid, indicating
net reabsorption of bicarbonate. When the initial perfusate contained no bicarbonate and the
bath contained 25 mM bicarbonate, total CO2 appeared in the collected tubule fluid. The …
Proximal straight tubules from rabbit kidneys were perfused in vitro in order to study transport of bicarbonate. Total CO2 content was measured in perfused and collected tubule fluid, using microcalorimetry. When the initial perfusate and bath contained 25 mM bicarbonate, the concentration of total CO2 decreased in the collected tubule fluid, indicating net reabsorption of bicarbonate. When the initial perfusate contained no bicarbonate and the bath contained 25 mM bicarbonate, total CO2 appeared in the collected tubule fluid. The rate at which total CO2 appeared in the tubule fluid was rapid, indicating a high permeability. Proximal straight tubules from superficial and juxtamedullary nephrons were compared and found to differ in permeability to CO2 and in transport rate. This functional heterogeneity may affect urinary acidification when there is redistribution of renal blood flow.
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