Njanoor Narayanan
Professor
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PH.D. University of Bombay |
Research in my laboratory is centered on the cellular and molecular mechanisms governing cytosolic Ca2+ concentration during the contraction-relaxation cycle of the heart under normal as well as various pathophysiological states including aging, hypertension, hypertrophy and heart failure. The primary focus of research in this regard is on transmembrane Ca2+ cycling by the sarcoplasmic reticulum (SR) and physiological mechanisms of its regulation. Our recent studies have revealed novel, Ca2+/calmodulin-dependent processes that are critical to the maintenance of normal Ca2+ sequestration and Ca2+ release functions of the SR. Impaired SR Ca2+ cycling and consequent impairment in cellular Ca2+ homeostasis, is a major feature underlying cardiac hypertrophy, and heart failure of diverse origin. Postmaturational aging is accompanied by significant myocyte loss, left ventricular hypertrophy, and high incidence diastolic dysfunction and heart failure. As part of the Heart and Stroke Foundation of Ontario Heart Failure Group (www.heartfailuregroup.uwo.ca), my laboratory offers the opportunity to investigate potential involvement of altered Ca2+/calmodulin-dependent processes in the pathogenesis of heart failure in various animal models as well as in humans.
Xu, A. and Narayanan, N. Reversible inhibition of the calcium-pumping ATPase in native cardiac sarcoplasmic reticulum: Evidence for calmodulin-dependent regulation of the Vmax of calcium transport. J. Biol. Chem. 275: 4407 -4416, 2000. Jiang, M., Xu, A., Tokmakejian, S. and Narayanan, N. Thyroid hormone-induced overexpression of functional ryanodine receptors in the rabbit heart. Am. J. Physiol. 278: H1429-H1438, 2000. Jiang, M., Xu, A., Jones, D.L. and Narayanan, N. Co-ordinate down regulation of ¦Ä-CaM kianse II and phospholamban accompanies contractile phenotype transition in the hyperthyroid rabbit soleus. Am. J. Physiol. 287: C622-C632, 2004. Sathish, V., Xu, A., Karmazyn, M. , Sims, S., and Narayanan, N. Mechanistic basis of differences in calcium handling properties of sarcoplasmic reticulum in the right and left ventricles of normal rat myocardium. Am. J. Physiol. (Heart Circ Physiol) 291: H88-H96, 2006. Jiang, M., Xu, A., and Narayanan, N. Thyroid hormone down regulates the expression and function of sarcoplasmic reticulum-associated CaM kinase II in the rabbit heart. Am. J. Physiol. (Heart Circ Physiol) 291: (First published April 14 2006; doi:10.1152/ajpheart.00875.2005)
