Oxidative stress and left ventricular function with chronic intermittent hypoxia in rats

Area of Science:

• Cardiovascular Physiology
• Sleep Medicine
• Oxidative Stress Research

Background:

• Obstructive sleep apnea (OSA) is linked to oxidative stress and myocardial dysfunction.
• The role of chronic intermittent hypoxia (CIH), a key feature of OSA, in causing these cardiac issues requires further investigation.

Purpose of the Study:

• To determine if CIH alone is sufficient to induce oxidative stress and left-ventricular (LV) myocardial dysfunction.
• To investigate the impact of CIH on blood pressure, LV function, and myocardial oxidative stress markers in a rat model.

Main Methods:

• Rats were exposed to CIH (nadir O2, 4-5%) for 8 hours/day, 5 days/week, for 5 weeks, with outcomes compared to healthy controls (HC).
• Measurements included blood pressure, echocardiographic and invasive LV function assessments, and myocardial oxidative stress indices (lipid peroxides, superoxide dismutase).

Main Results:

• CIH exposure resulted in increased LV weight/heart weight and LV dilation.
• Significant decreases in LV fractional shortening, LV dp/dtmax, and cardiac output were observed in the CIH group.
• Elevated myocardial lipid peroxides and reduced superoxide dismutase levels indicated increased oxidative stress in CIH rats.

Conclusions:

• Chronic intermittent hypoxia is sufficient to induce left-ventricular myocardial dysfunction.
• CIH exposure leads to significant oxidative stress within the myocardium.
• These findings highlight the detrimental cardiac effects of CIH, a core component of obstructive sleep apnea.