title: Acidification in the distal tubule of the Amphiuma kidney.
abstract: The acidification of the urine within the distal tubule of Amphiuma means was studied with micropuncture techniques. Antimony microelectrodes calibrated in vivo were used for measuring the intratubular pH and samples were taken for the determination of Na+- and Cl- -concentrations and for determining buffer lines within the HCO-3-CO2 buffer system. The TF/P Na+ was used as a relative length determinator and a significant acidification along the length of the tubule was found. The pH in the tubule was more acid than samples equilibrated at blood PCO2. This disequilibrium can be described in terms of an imbalance within the Henderson-Hasselbach formula or/and as a PCO2-gradient across the tubular wall. The calculated PCO2-gradient was found to be correlated to the arterial PCO2 and the acidification to the arterial pH. The greatest pH-gradient is generated in the collecting duct and in the bladder.
mesh_terms: D000136:Acid-Base Equilibrium; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007684:Kidney Tubules / Q000502:physiology*; D007686:Kidney Tubules, Distal / Q000502:physiology*; D008839:Microelectrodes; D010313:Partial Pressure; D014562:Caudata / Q000502:physiology*; D014882:Water-Electrolyte Balance
chemical_list: D001639:Bicarbonates