Impact of cold adaptation on cardiac tolerance to ischemia/reperfusion. Role of glucocorticoid and thyroid hormones

We have established that the continuous cold exposure (CCE, 4 degrees C, 4 weeks) causes cold adaptation, increases systolic blood pressure, exerts infarct-limiting effect during coronary artery occlusion (45 min) and reperfusion (2 h). The CCE increases adrenal weight, heart weight and triiodothyronine (T-3) level but does not change thymus, spleen weight, serum cortisol, corticosterone and thyroxin (T-4) levels. The long-term (4 degrees C, 8 h/day, 4 weeks) intermittent cold exposure (LICE) induces adaptation to the cold and increases T4 level. The brief (4 degrees C, 1.5 h/day, 4 weeks) intermittent cold exposure (BICE) also evokes adaptation to the cold but had no effect on the blood pressure, the cardiac tolerance to ischemia/reperfusion, and does not change thymus, spleen weight, serum cortisol, corticosterone, T-3 and T-4 levels.