Dr. Alicia Ortega Aguilar 

aortega@servidor.unam.mx

Characterization of the calcium transportation mechanisms through different submembrane fractions of muscle cells

OBJECTIVES

SUMMARY

The main events leading to muscle activation are: The electric depolarization of the sarcolemma followed by a massive output of calcium from the sarcoplasmic reticulum and the binding of calcium to the myofibrils in order for a contraction to take place. Calcium regulating proteins, like Ca+2 ATPase and the Na2/Ca+2 exchanger, are considered to be the most important membrane components regulating the expulsion of calcium through the membranes of normal, apoptosic and neoplastic cells. Integral membrane proteins are regulated by the lipid composition of the membrane, principally by cholesterol which has an inhibitory effect on the activity of calcium transporting proteins. An understanding of how the calcium transport mechanisms are regulated is essential to explaining the physiology and pathology of the muscle cell. The characterization of the calcium transport mechanisms through the transversal tubules of the fast, slow and diaphragm skeletal muscles gives elements with which to study the possible influence of the integrity of these mechanisms on muscle fatigue.

- The study of the thermodynamic properties of Ca+2 ATPase and the Na+/Ca+2 exchanger in native and cholesterol depleted membranes of the T-tubules gives us information as to how these proteins are regulated by cholesterol

- The study of the effect of drugs like calcium blockers and dehydroprostaglandin derivatives on the activity and thermal stability of calcium regulating proteins of the sarcolemma and the sarcoplasmic reticulum of the cardiac myocyte and skeletal muscular fiber helps us to understand the mechanism through which these drugs and extracellularly added phospholipids revert sarcolemmal damage produced mechanically and the deleterious effects of ischemia.

PARTICIPANTS

BIBLIOGRAPHY


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