Summary:
Cardiovascular diseases are major cause of deaths in United States and Worldwide. According
to American Heart Association (AHA), more than 2200 deaths reported every day with an average
of 1 in every 39 seconds. Arrhythmias and cardiomyopathy is also reported in many diseased
conditions including acute lung injury, diabetes, obesity, hypertension and cancer. Patients in
critical care or intensive care unit (ICU) are often administered with hyperoxia (PaO2 > 100
mmHg) for treatment with acute lung injury, congestive heart failure, cardiac fibrosis. However,
recent studies indicate that dysfunctional lung and compromised pulmonary functioning cause
increased workload on the heart and therefore lead to cardiac remodeling resulting in arrhythmias,
heart failure and death. Among all the ventilated patients, early estimates of mortality rates in
mechanical ventilation was as high as 40-45%. Additionally, existing reports suggests that more
than 50% of the population admitted to ICU are older adults with ages more than 60 years. Studies
also reported significantly higher in-hospital mortality in older adult population in ICU than younger
population without differences in the duration of mechanical ventilation. The exact nature of this
problem remains unknown. In this study we will investigate the genes involved in ventricular
remodeling and electrical remodeling in hyperoxia induced aged (older adult) mice hearts using
molecular, and biochemical methods and compared with young adult mice. These changes will
be further investigated for their roles in physiological changes occur in aged mice heart using
echocardiography, ECG and whole-cell patch-clamping techniques and will be compared with
young adult mice. Our preliminary data also suggests that exposure of mice to hyperoxia for 24h
is enough to initiate cardiac remodeling. Therefore, in this proposal we will identify the optimum
time of exposure for hyperoxia at which most of the pathophysiology induced by hyperoxia in aged
mice hearts can be reversed. We will also investigate the molecular mechanisms of ventricular
remodeling and electrical remodeling in hyperoxia conditions, knowing which not only important
to understand the disease development and progression, but also to develop targeted therapy for
the disease cure.