Randall K. Packer Professor of Biology Regulation of electrolyte balance and blood pressure Department of Biological Sciences The George Washington University Lisner Hall 348, 2023 G Street, NW Washington, D.C. 20052 Office: (202) 994-6977 Fax: (202) 994-6100 E-Mail: rkp@gwu.edu Dept E-mail : biology@gwu.edu

My early research interests were primarily in the areas of ion balance, respiration and acid-base balance in teleost fish. In my Ph.D. thesis research, Bill Dunson and I demonstrated for the first time that exposure to acidic environments interfered with ion balance in fresh water fish. Subsequent work by me and other investigators has shown that ion imbalance is the primary cause of death of fish during chronic exposure to acidic environments. At GW my students and I have also studied ion and acid-base balance in amphibians, reptiles, crabs and tunicates. While I remain interested in a number of problems involving epithelial transport, including recent work on fish gill ion transport, most of my work has been in mammalian renal physiology.

Since 1985 my students at GW and I have been investigating problems in mammalian kidney function, often in collaboration with Dr. Mark Knepper and other members of the Laboratory of Kidney and Electrolyte Metabolism, NHLBI, NIH. We have pursued several lines of work. including ion and water permeability characteristics of the papillary surface epithelium, several studies of different aspects of acid-base balance
and , most recently, a targeted proteomic approach to understanding of the role of kidneys in development of hypertension. We have a panel of antibodies specific for all important sodium ion transporters in the nephron. This enables us to follow changes in transporter abundance in response to specific physiological challenges or changes in regulatory pathways.

Turban S, Beutler KT, Morris RG, Masilamini S, Fenton RA, Knepper MA, Packer RK (2006) Long-Term Regulation of Proximal Tubule Acid-Base Transporter Abundance by Angiotensin II. In Press, Kidney International 60:660-668.

Tiwari S, Packer RK, HU X, Sugimura Y, Verbalis JG, Ecelbarger CA. (2006) Increased renal {alpha} - ENaC and NCC abundance and elevated blood pressure are independent of hyperaldosteronism in vasopressin escape. Am. J. Physiol. 291 (Renal Fluid Electrolyte Physiol.): F49-F57.

Beutler, K.T., Masilamini, S, Turban, S. Nielsen, J., Brooks, H.L., Ageloff, S., Fenton, R., Packer, R.K., and M.A. Knepper. (2003) Long-term regulation of ENaC expression in kidney by Angiotensin II. Hypertension 41:1143-1150.

Kim, G-H., S.W. Martin, P. Fernandez-Llama, S. Masilamani, R.K. Packer, and M.A. Knepper. (2000) Long-term regulation of renal Na-dependent cotransporters and EnaC: response to altered acid-base intake. Am. J. Physiol. 279 (Renal Fluid Electrolyte Physiol.): F459-F467.

Kim, G-H., C. Ecelbarger, C. Mitchell, R. Packer, J. Wade and M. Knepper. (1999)
Vasopressin increases Na-K-2Cl cotransporter expression in thick ascending limb of Henles loop. Am. J. Physiol. 276 (Renal Fluid Electrolyte Physiol. 31): F96-F103.

Kim, G-H., C. Ecelbarger, M..Knepper, and R. Packer (1999) Regulation of BSC-1, NHE-3 and Na+/K+ ATPase abundance in rat renal outer medulla by acid, base and sodium loading. J. Am. Soc. Neph. 10(5):935-942.

Packer, R.K. and J. Garvin (1998) Seasonal differences in activity of perch (Perca flavescens) gill Na+/K+ ATPase. Comp. Biochem Physiol.B: 120:777-783.

Nolan, P.J., M.A. Knepper and R.K. Packer (1997) Role of adrenal steroids in stimulating ammonium excretion during acute metabolic acidosis. Contrib. Nephrol. 121:55-61

Nolan, P.J., M.A. Knepper and R.K. Packer (1997) Inhibition of IMCD 11?-hydroxysteroid dehydrogenase type 2 by low pH and acute acid loading. J. Am. Soc. Neph. 8:530-534.

Packer, R, K. , C. Curry and K. Brown (1995) Urinary organic anion excretion in response to dietary acid and base loading. J. Am. Soc. Neph. 5:1624-1629.

Undergraduates:

Nils Schnor - Project topic - Is hypertension resulting from inhibition of 11-beta HSD2 due to changes in nephron sodium transporter abundance or distribution?

Amy Fiedler - Project Title - Regulation of 11-beta HSD2 abundance and function in response to a low sodium diet.

Jessica Lundin - Project Title - Regulation of 11-beta HSD2 abundance and function in response to restriction of water intake.