The mechanisms involved in the """"""""active"""""""" (uphill) extrusion of calcium from muscle cells, and in the regulation of steady Ca balance, are incompletely understood. Many types of cells, including invertebrate muscle and vertebrate smooth and cardiac muscle, employ a Ca transport mechanism in which Na ions exchange for Ca (""""""""Na/Ca exchange""""""""). Thus, the Na electrochemical gradient may provide at least some of the energy for Ca extrusion; moreover, Na/Ca exchange may also mediate Ca entry when Na electrochemical gradient is reduced. ATP also plays a role, in part via an effect on the Na/Ca exchange kinetics, and in part as fuel for a parallel Ca-ATPase driven """"""""Ca pump"""""""". Internally perfused single giant barnacle muscle cells are employed as a model system to study Ca transport and metabolism in muscle. During the forthcoming project period, characterization of the Na/Ca exchange system in barnacle muscle should be completed, including direct determination of the exchange stoichiometry, and the comparative properties of the forward (Na entry/Ca exit) and reverse (Ca entry/Na exit) modes of operation of the exchanger as well as the """"""""futile modes"""""""" (Ca/Ca and Na/Na) exchange. Of particular interest is the role of internal Ca and Na in the regulation of exchanger turnover. The information obtained from this model system will be applied to the study of Ca transport and metabolism in arterial smooth muscle (ASM) cells. Preliminary studies on rings of bovine tail artery (Progress Report) indicate that Na/Ca exchange plays a prominent role in the regulation of (Ca2+)i, the intracellular free Ca concentration, in this tissue. In the proposed experiments, a Ca-sensitive fluorescent dye (fura-2) and digital imaging methods will be used to measure (Ca2+)i in single, dissociated bovine tail ASM cells. (Ca2+)i will be measured in resting and activated cells, and following reduction of Na electrochemical gradient. The latter should provide direct information about the Na/Ca exchange system in these cells. Patch clamp methods, in conjunction with the imaging methods, will be used to measure the ionic currents associated with Na/Ca exchange, and to determine the factors that regulate Na/Ca exchange in ASM. The results of these experiments should provide new information about the relative importance of Na/Ca exchange and other (parallel) Ca transport systems in the regulation of (Ca2+)i in these cells. The results may be applicable to pathophysiological processes such as those associated with hypertension.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL045215-10
Application #
3364184
Study Section
Physiology Study Section (PHY)
Project Start
1990-07-01
Project End
1995-06-30
Budget Start
1993-07-01
Budget End
1994-06-30
Support Year
10
Fiscal Year
1993
Total Cost
Indirect Cost
Name
University of Maryland Baltimore
Department
Type
Schools of Medicine
DUNS #
003255213
City
Baltimore
State
MD
Country
United States
Zip Code
21201
Madbouly, Abeer; Wang, Tao; Haagenson, Michael et al. (2017) Investigating the Association of Genetic Admixture and Donor/Recipient Genetic Disparity with Transplant Outcomes. Biol Blood Marrow Transplant 23:1029-1037
Hamlyn, John M; Blaustein, Mordecai P (2016) Endogenous Ouabain: Recent Advances and Controversies. Hypertension 68:526-32
Lanzani, Chiara; Gatti, Guido; Citterio, Lorena et al. (2016) Lanosterol Synthase Gene Polymorphisms and Changes in Endogenous Ouabain in the Response to Low Sodium Intake. Hypertension 67:342-8
Blaustein, Mordecai P; Chen, Ling; Hamlyn, John M et al. (2016) Pivotal role of ?2 Na+ pumps and their high affinity ouabain binding site in cardiovascular health and disease. J Physiol 594:6079-6103
Song, Hong; Karashima, Eiji; Hamlyn, John M et al. (2014) Ouabain-digoxin antagonism in rat arteries and neurones. J Physiol 592:941-69
Blaustein, Mordecai P (2014) Why isn't endogenous ouabain more widely accepted? Am J Physiol Heart Circ Physiol 307:H635-9
Hamlyn, John M; Linde, Cristina I; Gao, Junjie et al. (2014) Neuroendocrine humoral and vascular components in the pressor pathway for brain angiotensin II: a new axis in long term blood pressure control. PLoS One 9:e108916
Song, Hong; Thompson, Scott M; Blaustein, Mordecai P (2013) Nanomolar ouabain augments Ca2+ signalling in rat hippocampal neurones and glia. J Physiol 591:1671-89
Hamlyn, John M; Blaustein, Mordecai P (2013) Salt sensitivity, endogenous ouabain and hypertension. Curr Opin Nephrol Hypertens 22:51-8
Pulina, Maria V; Zulian, A; Baryshnikov, Sergey G et al. (2013) Cross talk between plasma membrane Na(+)/Ca (2+) exchanger-1 and TRPC/Orai-containing channels: key players in arterial hypertension. Adv Exp Med Biol 961:365-74

Showing the most recent 10 out of 60 publications