In Amphiuma red blood cells, the Na/H and K/H antiports mediate volume regulation after shrinkage and swelling, respectively. These ionic flux routes play a crucial role in viability of certain tumor cells and are directly responsible for cell injury in cardiomyocites during hypoxic episodes. However, the basis for their activation and inactivation remains obscure. We hypothesize that antiport protein phosphorylation status determines activity, while phosphorylation pattern dictates ion selectivity. To test this hypothesis we will monitor transporter activity in conjunction with biochemical studies designed to evaluate transporter phosphorylation state in order to address the following specific aims: 1) Determine the effect of the phosphatase inhibitor Calyculin A in the ionic fluxes through the Na/H and K/H exchange. 2) Perform experiments to determine the time course for activation and inactivation of the Alkali Metal/H exchanger during hyperosmotic and hyposmotic perturbations and fit the data to a minimal two state model (active and inactive) proposed by Jennings, M.L. and Al-Rohil, N. (1990). 3) Determine which antiporter amino acid residues are phosphorylated or dephosphorylated in response to shrinkage or swelling.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Predoctoral Individual National Research Service Award (F31)
Project #
5F31GM018985-02
Application #
2749765
Study Section
Minority Programs Review Committee (MPRC)
Project Start
1998-08-01
Project End
Budget Start
1998-08-01
Budget End
1999-07-31
Support Year
2
Fiscal Year
1998
Total Cost
Indirect Cost
Name
University of California Davis
Department
Physiology
Type
Schools of Medicine
DUNS #
094878337
City
Davis
State
CA
Country
United States
Zip Code
95618
Ortiz-Acevedo, Alejandro; Rigor, Robert R; Maldonado, Hector M et al. (2010) Coordinated control of volume regulatory Na+/H+ and K+/H+ exchange pathways in Amphiuma red blood cells. Am J Physiol Cell Physiol 298:C510-20
Ortiz-Acevedo, Alejandro; Rigor, Robert R; Maldonado, Hector M et al. (2008) Activation of Na+/H+ and K+/H+ exchange by calyculin A in Amphiuma tridactylum red blood cells: implications for the control of volume-induced ion flux activity. Am J Physiol Cell Physiol 295:C1316-25