Kidney Treks 2013 Rotation D2 Ashish Sharma, Erin McIntosh, Karen Hong, Elyse Sadow, Jared Maul-a-tortoise Acid-Base Module

Principal Cells of Collecting Duct Na + ATP K+K+ H+H+ H + ATPase Na + ATP K+K+ Na + ENaC H+H+ H + ATPase BasolateralApical Cl - Na + H+H+

Set-up

Experiment A

Principal Cells of Collecting Duct Na + ATP K+K+ H+H+ H + ATPase Na + ATP K+K+ Na + ENaC H+H+ H + ATPase BasolateralApical Amiloride H+H+

Experiment A Amiloride

CO 2 + H 2 O Carbonic anhydrase ATP H+H+ HCO 3 - Cl - ATP Na + K+K+ H+H+ H+H+ H+H+ H+H+ H+H+ Intercalated Cells of Collecting Duct HCO 3 - Basolateral Apical H+H+

Experiment A AmilorideHCO 3 -

CO 2 + H 2 O Carbonic anhydrase ATP H+H+ HCO 3 - Cl - ATP Na + K+K+ H+H+ H+H+ H+H+ H+H+ H+H+ Intercalated Cells of Collecting Duct HCO 3 - Basolateral Apical Acetazolamide

Experiment A AmilorideHCO 3 - Acetazolamide

You’re my boy, Tom!

Principal Cells of Collecting Duct Na + ATP K+K+ H+H+ H + ATPase Na + ATP K+K+ Na + ENaC H+H+ H + ATPase BasolateralApical Amiloride Bafilomycin

Experiment B Ringers +sulfate Amiloride HCO 3 - Bafilomycin Acetazo -lamide

Conclusions and Next Steps Group D1 postulated that the negative current resulted from H+ flux Amiloride Bicarbonate We proved this using direct and indirect blocking Acetazolamide Bafilomycin Explore renal tubule acidosis (RTA) using this model

Acid-Base Set-up SPOTTED! FACE OF IMPENDING DOOM SODIUM CITRATE AMMONIUM CHLORIDE

Urine pH Time (hours) pH

Urine pH Time (hours) pH Ashish’s emesis

Acid-Base Experiment: Mechanism Ions in the lumenConcentration (mEq) Na + 20 K+K+ 10 NH (solved for) Cl - 90 HCO Total0 Na + + K + + NH 4 + = Cl - + HCO 3 -

Calculations pH = pKa + log([HCO 3 - ]/[H 2 CO 3 ]) [H 2 CO 3 ] = k HCO2 *pCO = log([HCO 3 - ]/[0.03*40]) [HCO 3 - ] = 0.1

Bicarbonate Juncos et al. 2000

Trends in Chloride Time (hours) Cl - (mEq) ASHISH!

Observations Acid and Base load decreased and increased urine pH respectively. We also followed up at longer time intervals to explore possible longer changes in urine composition. Base load increased bicarbonate excretion, which necessitates cation excretion to neutralize the negative charge. Acid load increased chloride excretion though it began to return to baseline by 9 hours.

Making dad proud…

Acknowledgements Dr. Schwartz Drs. McGrath Dr. MacIver Dr. Thomas Maren