Physiological Responses to Intermittent Environmental Heat Stress in Mice

Intermittent heat stress in C57BL/6J mice (30-37°C, 3 h/day, 4 days/week, up to 4 weeks) produced a neuroendocrine stress response with 2-4-fold higher plasma corticosterone, >50% lower epinephrine, and ~10 mmHg lower systolic and diastolic blood pressure. Despite >30% depletion of circulating immune cells, leukocyte rolling and adhesion to vascular endothelium rose more than 3-fold, indicating endothelial activation that precedes cardiovascular dysfunction. Cardiac systolic function, arterial stiffness, plasma lipids, and organ injury markers were largely unaffected.