Health Sciences Center
Hospital and Clinic
Primate Center
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Tropical Medicine

Professor

MBBS: The Chittagong University, Bangladesh
Ph.D.: University of Leeds, England

Research activities in my laboratory are mainly focused on the elucidation of the intrarenal mechanisms regulating renal hemodynamics and renal function. Current investigations in my laboratory are directed at determining how endothelial derived vasoactive factors contribute to the regulation of renal hemodynamics and renal excretory function. Studies to characterize the role of an endothelial derived vasodilator agent, nitric oxide (NO) in regulating renal function have been approached in our laboratory via analysis of the responses to pharmacological blockade of endogenous NO synthesis as well as the intra-renal administration of exogenous NO donors and NO agonists. The level of intrarenal NO activity is determined by the use of a NO sensitive micro-electrode. Renal regional blood flow responses to alteration in intrarenal NO activity is assessed with the aid of laser Doppler needle flowmetry. The results of these studies over the years indicate that endogenous NO exerts an important role in the regulation of renal hemodynamics as well as tubular transport of sodium. We have also recently directed our efforts to elucidate the interactions between reactive oxygen species, particularly the superoxide anion (O2- ) and NO in the control of renal regional blood flow as well as salt and water excretion. This interaction of O2- and NO has been a major focus of many recent studies as it is known that the biological half life of NO in the living tissue can be reduced by the presence of O2-. An imbalance between the formation and regulation of these two opposing factors (NO and O2-) impairs the normal renal vascular and tubular function and thus may lead to some patho-physiological conditions such as hypertension. Angiotensin II (ANGII) administration has been shown to induce production of O2- as well as NO. Studies are now being carried out to examine the hypothesis that impairment of this interaction between O2- and NO in the regulation of renal function during altered state of renin-angiotensin system may be involved in the development of ANGII dependent hypertension. Assessment of such interactions between NO and O2- are being made in acute as well as chronic experimental animal preparations, evaluating the responses to administration of O2- scavengers and NO synthase inhibitors on renal regional blood flows and renal excretory function with the aid of laser-Doppler flowmetry and NO sensitive micro-electrode. We anticipate that these studies will provide a more comprehensive understanding of how these free radical factors interact with each other to provide a co-ordinated regulation of renal cortical and medullary circulation and excretory function under normal conditions as well as in ANGII dependent hypertension.

Recent Publications:

A PubMed listing of research publications for Dewan S.A. Majid, Ph.D.

Contact:

majid@tulane.edu
504 988-2600