George J. Schwartz, M.D.
The Schwartz laboratory is determining how intercalated cells of the kidney cortical collecting duct (CCD) sense a change in extracellular pH and adapt by reversing their polarity of H+/HCO3 transporters. After exposure to a 3 h incubation at pH 6.8, rabbit CCDs, which normally secrete HCO3, reverse polarity, secrete H+ and endocytically remove apical Cl/HCO3 exchangers to stop HCO3 secretion. The novel protein hensin is expressed in the extracellular matrix (ECM) surrounding adapting HCO3-secreting intercalated cells (B-ICs) and plays a key role in this adaptation. Schwartz also runs the Central Biochemistry Laboratory for the NIH-funded CKiD North American study of children with kidney disease. His group has developed an iohexol plasma disappearance test to accurately measure kidney filtration rates in children. This test is being requested by dozens of other potential collaborators.