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August 15, 2026Journal of the American College of Cardiology262 citationsOpen Access

Impact of Beta-Myosin Heavy Chain Expression on Cardiac Function During Stress

Impact of beta-myosin heavy chain expression on cardiac function during stress

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Why the study?

A shift from alpha- to beta-MHC occurs in failing hearts, but its impact on disease progression and cardiac function under chronic stress is not well understood.

Does a pre-existing shift from alpha- to beta-MHC affect cardiac function under chronic mechanical or pharmacologic cardiovascular stress in mice?

Population

Transgenic mice with replacement of alpha- with beta-MHC and non-TG mice

Comparison

Beta-MHC transgenic mice vs non-transgenic mice under chronic mechanical or pharmacologic cardiovascular stress

Design

Transgenic animal study

Key result

Transgenic expression of beta-MHC in mice resulted in augmented LV hypertrophy, decompensation, and accelerated dilation under severe cardiovascular stress compared to non-transgenic mice.

Authors

MKMaike KrenzJRJeffrey Robbins

Discussion

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Overview

Hypothesis-generating only; leaves open MHC isoform modulation as a HF target.

Key Points

  • To determine how a pre-existing isoform shift from alpha- to beta-myosin heavy chain impacts cardiac structure and function during chronic mechanical and pharmacological stress.
  • Generated transgenic mice with near-complete replacement of alpha-myosin heavy chain with beta-myosin heavy chain.
  • Subjected transgenic and non-transgenic mice to mechanical stress via a four-week swimming protocol.
  • Induced chronic cardiovascular stress via isoproterenol infusion and surgical myocardial infarction models.
  • Four weeks of swimming increased left ventricular-to-body weight ratios by 20% in both transgenic and non-transgenic mice, with transgenic mice showing mildly larger ventricular diameters without overt failure.
  • Chronic isoproterenol stimulation induced augmented left ventricular hypertrophy accompanied by left ventricular decompensation specifically in transgenic mice.
  • Post-infarction transgenic hearts demonstrated accelerated left ventricular dilation and a accelerated decline in shortening fraction compared to controls.

Structured PICO

Does a pre-existing shift from alpha- to beta-MHC affect cardiac function under chronic mechanical or pharmacologic cardiovascular stress in mice?

P
Population
Transgenic mice with near-complete replacement of alpha- with beta-MHC subjected to chronic mechanical or pharmacologic cardiovascular stress.
E
Exposure
Cardiac stress (four weeks of swimming, chronic isoproterenol stimulation, or post-infarction failure model)
C
Comparator
Non-transgenic mice subjected to the same cardiac stress
O
Outcome
Cardiac function and ventricular morphology (including LV/body weight ratios, LV diameters, and shortening fraction)surrogate

The shift from alpha- to beta-myosin heavy chain isoform observed in cardiac disease appears to be a maladaptive response that worsens cardiac function under severe cardiovascular stress.

Cite This Study

Krenz et al. (2004) studied Cardiovascular stress. Transgenic beta-myosin heavy chain (beta-MHC) expression vs. Non-transgenic mice was evaluated on Cardiac function and ventricular morphology under stress. Transgenic expression of beta-MHC in mice resulted in augmented LV hypertrophy, decompensation, and accelerated dilation under severe cardiovascular stress compared to non-transgenic mice.

synapsesocial.com/papers/6a7fdaa5fcbf2b1afafe78d4https://doi.org/10.1016/j.jacc.2004.09.044
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