Lecture 4 - NPB113 4-1 Excitation-Contraction Coupling...

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1 January 13, 2010 NPB113 4-1 Excitation-Contraction Coupling Outline Definition Excitation-Contraction Coupling Sequence of Events Calcium Current and Calcium Release from Sarcoplasmic Reticulum (SR) Calcium Induced Calcium Release from the SR Calcium Removal from Sarcoplasm Reuptake into SR Extrusion across Sarcolemma Relationship between Sarcoplasmic Calcium and Force of Cardiac Muscle. Regulation of Sarcoplasmic Calcium through Rate of Delivery of Calcium to the Sarcoplasm Rate of Removal of Calcium from the Sarcoplasm Affect of Heart Rate on Sarcoplasmic Calcium and Force of Cardiac Muscle Contraction .
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2 January 13, 2010 NPB113 Excitation-Contraction Coupling 4-2 Excitation-Contraction Coupling Sequence of events from depolarization of the cardiac muscle cell to onset of contraction. Coupling occurs through Ca++ which enables actin-myosin crossbridge Structure Muscle Cell Sarcolemma T-tubule Longitudinal Sarcoplasmic Reticulum & Lateral Sacs – uptake and storage of Ca++. Ca++ stored and released from Lateral Sacs Sarcomere – Z line, Actin with regulatory proteins tropomyosin & troponin, Myosin. Voltage gated Dihydropyridine (DHP) Ca Channels (L Ca Channels) T-Tubule. Ca++ gated Ryanodine (Ry) Channels Lateral Sacs SERCA
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3 January 13, 2010 NPB113 Excitation-Contraction Coupling 4-3 Sequence of Events SERCA
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4 January 13, 2010 NPB113 Excitation-Contraction Coupling 4-4 Sequence of Events, Reuptake of Sarcoplasmic Calcium For cross-bridge formation to occur sarcoplasmic Ca++ must be at least 10 -5 M. Unlike skeletal muscle, the quantity Ca++ released insufficient to mobilize all myosin binding sites on the actin myofilaments (40% of available cross-bridges mobilized). Therefore, the number of binding sites mobilized &
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This note was uploaded on 04/09/2010 for the course NPB npb 113 taught by Professor Goldberg during the Spring '10 term at UC Davis.

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Lecture 4 - NPB113 4-1 Excitation-Contraction Coupling...

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