Cardiac myosin (activator)

Class

Selective cardiac myosin activator

Notes

original target text: Cardiac myosin (activator) | original target text: Cardiac myosin (activator) (agonist)

Cardiac myosin is the motor protein inside heart muscle cells that generates the mechanical force of each heartbeat. During contraction, myosin heads cyclically attach to actin filaments, pull against them using energy from ATP, and then release, producing the shortening of muscle fibers that ejects blood from the ventricle. A selective cardiac myosin activator binds directly to this motor protein and increases the fraction of myosin heads that enter the force-producing, actin-bound state during each contraction. This is a different strategy from traditional drugs that increase heart muscle contraction by raising intracellular calcium levels, since it acts directly on the contractile machinery rather than on the signals that trigger it. The biological rationale is to improve the pumping strength of a weakened heart, relevant in conditions where the ventricle does not contract forcefully enough to move sufficient blood, broadly termed systolic heart failure. Because the approach bypasses calcium signaling, it is of interest as a way to strengthen contraction without some of the downstream effects on calcium handling that have historically limited older inotropic therapies. The overall aim is to restore mechanical pump function in heart failure while minimizing added strain on the heart's oxygen supply and rhythm stability.