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Abnormal intracellular calcium handling in myocardium from patients with end-stage heart failure
Insights
Heart failure impairs intracellular calcium handling, prolonging muscle contractions and causing abnormal calcium transients. This directly links calcium dysregulation to systolic and diastolic dysfunction in failing human hearts.
Area of Science:
- Cardiology
- Molecular Biology
- Physiology
Background:
- Normal cardiac function relies on precise intracellular calcium (Ca2+) release and reuptake for muscle contraction and relaxation.
- Dysfunctional Ca2+ handling is implicated in heart failure but direct evidence in human myocardium is limited.
Purpose of the Study:
- To investigate intracellular Ca2+ handling during active contraction in human heart failure.
- To determine if abnormal Ca2+ transients correlate with systolic and diastolic dysfunction in heart failure.
Main Methods:
- Intracellular Ca2+ transients were measured using aequorin luminescence.
- Isometric contractions were recorded from human myocardium samples.
- Samples were obtained from patients with end-stage heart failure and compared to controls.
Main Results:
- Contractions and Ca2+ transients were significantly prolonged in failing heart muscle compared to controls.
- Ca2+ transients in heart failure exhibited two distinct components.
- Failing hearts demonstrated a reduced ability to lower resting Ca2+ levels during diastole.
Conclusions:
- Direct evidence shows abnormal intracellular Ca2+ handling in actively contracting human heart failure myocardium.
- Altered Ca2+ dynamics contribute to both systolic and diastolic dysfunction in heart failure.
- These findings highlight Ca2+ dysregulation as a key mechanism in heart failure pathophysiology.
Abstract:
Intracellular Ca2+ release and reuptake are essential for contraction and relaxation of normal heart muscle. Intracellular Ca2+ transients were recorded with aequorin during isometric contraction of myocardium from patients with end-stage heart failure. In contrast to controls, contractions and Ca2+ transients of muscles from failing hearts were markedly prolonged, and the Ca2+ transients exhibited 2 distinct components. Muscles from failing hearts showed a diminished capacity to restore low resting Ca2+ levels during diastole. These experiments provide the first direct evidence from actively contracting human myocardium that intracellular Ca2+ handling is abnormal and may cause systolic and diastolic dysfunction in heart failure.