Mechanisms of the Frank-Starling Law of the Heart: The Beat Goes On

Cellular and molecular mechanisms remain elusive nearly a century after Frank Starling and colleagues demonstrated that an increase in ventricular filling promotes an increase in developed pressure. Textbooks indicate that changes in filament overlap with stretch of ventricular muscle in the rising phase of the length-tension relation are the main mechanism, but this cannot account for the much steeper dependence of tension on sarcomere length in heart versus skeletal muscle. Solaro tries to resolve the puzzle of Frank-Starling's law regarding the mechanism active force generation becomes more sensitive to Casup2+.