Author

Oies Hussein

Date of Award

2011

Degree Type

Thesis

Degree Name

Master of Science

Program

Physiology and Pharmacology

Supervisor

Dr. John MacDonald

Second Advisor

Dr. Michael Jackson

Abstract

The interaction of Ca2+-calmodulin is known to promote Ca2+-dependent negative feedback on the activity of various Ca permeable channels through Ca -dependent inactivation. Our laboratory has previously observed a progressive, time-dependent inactivation of TRPM2 (melastatin-related transient receptor potential channel 2). Currents were evoked from HEK 293T cells stably expressing TRPM2, through-the intracellular application of ADPR. TRPM2-mediated currents developed rapidly, reaching a peak and decaying to a steady state in the continued presence of extracellular Ca2+. Full recovery of TRPM2 channels from inactivation was dependent on ADPR concentration. Inactivation was reduced at more depolarized membrane potentials, consistent with a reduced driving force and influx of Ca2+. The extent of inactivation was dependent on extra- and intracellular Ca2+. Exogenous application of calmodulin results in a slower recovery of TRPM2 channels, in addition to increased inactivation. In conclusion, I have shown that TRPM2 channels are susceptible to Ca2+-dependent inactivation involving calmodulin.

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