A basic understanding of the cell in health and disease is essential if we are to understand more complex tissue, organ and organisms function. The major goals listed in the previous application for funds were 1) define kinetic and thermodynamic criteria useful in identification of alkali metal/H exchange, 2) investigate underlying control of alkali metal/H exchange, and 3) apply the model to analysis of cell volume disturbances (cardiac) in isotonic media. Our goal with regard to the first point has been largely realized. With respect to point 2, we have identified a number of activators of alkali metal/H exchange, completed studies of pH regulation ,and gained an understanding of anion effects. The control of Na/H exchange is sufficiently complex that we have begun biochemical studies in order to appropriately address the problem. In regard to point 3, we have applied NMR to Na transport by red cells and heart. The first phase of the studies evaluating the role of Na/H exchange in hypoxic cell damage is progressing nicely. In summary, aims for the period for which funds are requested are logical extensions of those previously stated. We propose to build upon our previous achievements, extending the applications and ideas developed through our past efforts. Thus, the proposal for funds is focused on increasing understanding of a fundamental cellular process, the Na/H exchanger. The Na/H exchange is broadly distributed and plays a central role in a variety of cellular processes which include (1) cell volume regulation, (2) cell pH regulation, (3) normal and abnormal cell growth, and (4) fluid-electrolyte and acid- base balance at the level of the organism. In light of the above, we propose to identify the Na/H exchange protein and ultimately evaluate its role as a kinase substrate in response to a variety of stimuli known to activate the exchanger. These studies will be performed employing conventional chemical and biochemical methods, using the Amphiuma red blood cell as a model. A second phase of the proposed studies is to evaluate the contribution of Na/H exchange to hypoxic/ischemic injury in the Langendorff perfused rabbit heart using NMR spectroscopy. We hypothesize that during hypoxia and ischemia the Na/H exchanger, operating in a pH regulatory role, causes Na uptake, cell swelling, Ca entry and ultimately cell death. By employing 23Na, 31P and 19F (BAPTA) spectroscopy and thermodynamic and pharmacologic criteria, we will evaluate Na/H exchange flux and its interplay with Na/Ca exchange, the Na-K pump and ultimately cell metabolism during hypoxia. The information to be obtained in the second phase is clinically significant as it relates to organ preservation and shipment for transplant, open heart surgery, shock, stroke, trauma and the like.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL021179-15
Application #
3336412
Study Section
Physiology Study Section (PHY)
Project Start
1978-04-01
Project End
1994-11-30
Budget Start
1992-12-01
Budget End
1993-11-30
Support Year
15
Fiscal Year
1993
Total Cost
Indirect Cost
Name
University of California Davis
Department
Type
Schools of Medicine
DUNS #
094878337
City
Davis
State
CA
Country
United States
Zip Code
95618
Rigor, Robert R; Damoc, Catalina; Phinney, Brett S et al. (2011) Phosphorylation and activation of the plasma membrane Na+/H+ exchanger (NHE1) during osmotic cell shrinkage. PLoS One 6:e29210
Nygaard, Eva B; Lagerstedt, Jens O; Bjerre, Gabriel et al. (2011) Structural modeling and electron paramagnetic resonance spectroscopy of the human Na+/H+ exchanger isoform 1, NHE1. J Biol Chem 286:634-48
Liu, Hong; Cala, Peter M; Anderson, Steve E (2010) Na/H exchange inhibition protects newborn heart from ischemia/reperfusion injury by limiting Na+-dependent Ca2+ overload. J Cardiovasc Pharmacol 55:227-33
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
Pedersen, Stine Falsig; Cala, Peter Michael (2004) Comparative biology of the ubiquitous Na+/H+ exchanger, NHE1: lessons from erythrocytes. J Exp Zool A Comp Exp Biol 301:569-78
Liu, H; Cala, P M; Anderson, S E (1998) Ischemic preconditioning: effects on pH, Na and Ca in newborn rabbit hearts during Ischemia/Reperfusion. J Mol Cell Cardiol 30:685-97
Liu, H; Cala, P M; Anderson, S E (1997) Ethylisopropylamiloride diminishes changes in intracellular Na, Ca and pH in ischemic newborn myocardium. J Mol Cell Cardiol 29:2077-86
Cala, P M; Maldonado, H M (1994) pH regulatory Na/H exchange by Amphiuma red blood cells. J Gen Physiol 103:1035-53
Maldonado, H M; Cala, P M (1994) Labeling of the Amphiuma erythrocyte K+/H+ exchanger with H2DIDS. Am J Physiol 267:C1002-12

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