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Updated: Jun 10, 2026
Isolation, Culture, and Functional Characterization of Adult Mouse Cardiomyoctyes
Published on: September 24, 2013
Cardiac function is not significantly diminished in hearts isolated from young caveolin-1 knockout mice
Ava K Chow1, Edwin E Daniel, Richard Schulz
1Department of Pediatrics, Cardiovascular Research Centre, University of Alberta, Edmonton, Alberta, Canada.
Abstract:
Matrix metalloproteinases (MMPs) are known to degrade components of the extracellular matrix. More recently, in myocardial oxidative stress injury including ischemia-reperfusion, MMP-2 is activated and degrades troponin I and α-actinin. MMP activity is regulated at several levels. We recently showed that MMP-2 is localized in the caveolae of cardiomyocytes and is negatively regulated by caveolin-1 (Cav-1). The caveolin scaffolding domain of Cav-1 inhibits MMP-2 proteolytic activity in vitro, and Cav-1(-/-) mouse hearts have increased MMP-2 activity compared with controls. Whether this increase in MMP-2 activity translates to impaired cardiac function is unknown. Hearts isolated from Cav-1(-/-) mice and their wild-type controls were perfused as isolated working hearts and physiologically challenged with increasing increments of left atrial preload (7-22.5 mmHg). The hearts were then pharmacologically challenged with increasing concentrations of isoproterenol (0.1-100 nM). Functionally, the Cav-1(-/-) hearts were similar to the controls in heart rate, peak systolic pressure, developed pressure, and rate pressure product. At higher preload pressures, the Cav-1(-/-) hearts outperformed the control hearts. Coronary flow was significantly higher in Cav-1(-/-) hearts under all conditions. The highest concentration of isoproternol increased the heart rate of Cav-1(-/-) hearts more than in controls. Western blot analysis revealed no significant changes in troponin I or α-actinin between Cav-1(-/-) hearts and their controls. There was a significant loss of MMP-2 from both knockout and control hearts during the perfusion. In summary, despite the loss of Cav-1, Cav-1(-/-) hearts show similar or better cardiac function compared with wild-type hearts following physiological challenge or β-adrenergic stimulation in vitro, and this appears unrelated to changes in MMP-2.
Insights
Mice lacking caveolin-1 (Cav-1) showed similar or improved cardiac function compared to controls, despite altered matrix metalloproteinase-2 (MMP-2) activity. This suggests Cav-1 loss does not impair heart performance under physiological or pharmacological stress.
Area of Science:
- Cardiovascular Biology
- Molecular Cardiology
- Extracellular Matrix Biology
Background:
- Matrix metalloproteinases (MMPs), particularly MMP-2, degrade extracellular matrix components and cardiac proteins like troponin I and α-actinin during oxidative stress.
- Caveolin-1 (Cav-1) negatively regulates MMP-2 activity within cardiomyocyte caveolae, with Cav-1 knockout (Cav-1(-/-)) hearts exhibiting increased MMP-2 activity.
- The functional consequences of increased MMP-2 activity due to Cav-1 deficiency on cardiac performance were previously unknown.
Purpose of the Study:
- To investigate the impact of caveolin-1 deficiency on cardiac function under physiological and pharmacological stress.
- To determine if increased MMP-2 activity in Cav-1(-/-) hearts leads to impaired cardiac performance or altered protein degradation.
Main Methods:
- Isolated working heart preparations from Cav-1(-/-) and wild-type control mice were used.
- Hearts were subjected to physiological challenges (increasing left atrial preload) and pharmacological challenges (isoproterenol stimulation).
- Cardiac function parameters (heart rate, pressure, coronary flow) and protein levels (troponin I, α-actinin) were assessed.
Main Results:
- Cav-1(-/-) hearts exhibited similar or superior cardiac function compared to controls under various preload conditions.
- Coronary flow was significantly higher in Cav-1(-/-) hearts.
- Isoproterenol increased heart rate more in Cav-1(-/-) hearts, and no significant changes in troponin I or α-actinin degradation were observed between groups.
Conclusions:
- Loss of caveolin-1 does not impair cardiac function and may even enhance performance under stress.
- The increased MMP-2 activity in Cav-1(-/-) hearts does not translate to functional deficits or altered degradation of key cardiac proteins.
- Cardiac function in Cav-1 deficient hearts appears independent of MMP-2 activity changes.
