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Updated: Oct 10, 2026
In vitro Assessment of Myocardial Protection following Hypothermia-Preconditioning in a Human Cardiac Myocytes Model
Published on: October 27, 2020
Heat shock protects cardiomyocytes from hypoxia-mediated apoptosis by attenuation of nitric oxide
F Y Bhora1, R M Wise, A H Foster
1Division of Cardiothoracic Surgery, George Washington University Medical Center, Washington, DC 20037, USA. FYBhora@aol.com
Insights
Heat shock (HS) protects heart cells from programmed cell death caused by low oxygen. This protective effect against hypoxia-induced apoptosis appears to be mediated by nitric oxide (NO).
Area of Science:
- Cardiology
- Cell Biology
- Biochemistry
Background:
- Heat shock (HS) is known to reduce myocardial necrosis.
- The effect of HS on apoptosis in cardiomyocytes (CM) is not well understood.
- Hypoxia induces apoptosis and nitric oxide (NO) production in the heart.
Purpose of the Study:
- To investigate if HS protects CM from hypoxia-induced apoptosis.
- To determine if this protection is mediated by NO.
Main Methods:
- CM were isolated from young rats and exposed to HS (42°C) or normal temperature (37°C).
- Cells were subjected to hypoxia followed by reoxygenation.
- Apoptosis was measured using TUNEL assay and c-myc protein detection.
- NO levels were quantified using the Griess reaction.
Main Results:
- CM viability remained high (>85%) across experimental groups.
- Statistical significance was observed (p < 0.01, ANOVA).
Conclusions:
- HS may protect CM against hypoxia-induced apoptosis.
- The protective mechanism may involve modulation of NO pathways.
Background:
Considerable data exists on the beneficial effect of Heat Shock (HS) on myocardial necrosis. However, the effect of HS on apoptosis or programmed cell death, the other mode of cell death in the heart, is unknown. Hypoxia leads to apoptosis and increased nitric oxide (NO) production in myocardium. NO has also been shown to cause apoptosis. We sought to investigate if HS could protect cardiomyocytes (CM) from hypoxia-induced apoptosis and if this protection was NO-mediated.
Materials And Methods:
CM were isolated from 1-2 day old rats and incubated at 37 degrees C or exposed to HS at 42 degrees C for 90 minutes before overnight incubation. CM were then subjected to hypoxic incubation in an argon/CO2 chamber (O2 concentration between 0.8-1.3 parts per million) for 90 minutes, followed by reoxygenation for 24 hours. Apoptosis was measured at 48 hours by TUNEL assay for in-situ DNA fragmentation and by immunohistochemical detection of c-myc protein, a proto-oncogene upregulated with apoptosis (grade 0 = no stain; +++ = most dense stain). NO was detected using the Griess reaction (nM +/- SEM). N > 5 for each group, performed in triplicate.
Results:
CM viability demonstrated by spontaneously beating cells in culture and trypan blue staining was > 85%. (*, # = p < 0.01, ANOVA).
