positive regulation of cardiac muscle cell contraction

Definition

Target type: biologicalprocess

Any process that activates or increases the frequency, rate or extent of cardiac muscle cell contraction. [PMID:19525381]

Positive regulation of cardiac muscle cell contraction is a complex process that involves a coordinated interplay of electrical, chemical, and mechanical events. It starts with the generation of an action potential in the sinoatrial node, the pacemaker of the heart. This electrical signal then propagates through the cardiac muscle cells via gap junctions, triggering a cascade of events that ultimately lead to muscle contraction.

The arrival of the action potential at the sarcolemma, the plasma membrane of the muscle cell, opens voltage-gated calcium channels, allowing calcium ions to flow from the extracellular space into the sarcoplasm, the cytoplasm of the muscle cell. This influx of calcium triggers the release of a larger amount of calcium from the sarcoplasmic reticulum (SR), a specialized organelle responsible for storing and releasing calcium in muscle cells.

The increased intracellular calcium concentration binds to troponin, a protein complex associated with tropomyosin, another protein that wraps around the thin filaments of the sarcomere, the basic unit of muscle contraction. Binding of calcium to troponin causes a conformational change in tropomyosin, exposing the myosin binding sites on the actin filaments.

Myosin, a motor protein, can now bind to actin, forming cross-bridges. The myosin head then undergoes a power stroke, pulling the actin filament toward the center of the sarcomere. This process requires ATP, which provides the energy for the myosin head to detach from actin and re-attach to a new binding site, repeating the cycle of cross-bridge formation and power stroke.

As calcium levels decline, either due to the removal of calcium from the sarcoplasm back into the SR or by the action of calcium pumps, troponin reverts to its resting state, covering the myosin binding sites on actin, and the muscle relaxes.

The process of positive regulation of cardiac muscle cell contraction is therefore a dynamic process, tightly regulated by the interplay of electrical, chemical, and mechanical signals. This intricate interplay ensures that the heart beats rhythmically and with sufficient force to pump blood throughout the body.'
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Proteins (1)

Compounds (4)