Cardioprotective effect of chronic hypoxia is blunted by concomitant hypercapnia

• Published in: Physiological research Vol. 52; no. 2; pp. 171 - 175
• Main Authors: Neckár, J, Sźárszoi, O, Herget, J, Ostádal, B, Kolár, F
• Format: Journal Article
• Language: English
• Published: Czech Republic 2003
• Subjects: Animals; Blood Pressure; Body Weight; Chronic Disease; Heart Rate; Hematocrit; Hypercapnia - complications; Hypercapnia - physiopathology; Hypoxia - complications; Hypoxia - physiopathology; Male; Myocardial Infarction - complications; Myocardial Infarction - physiopathology; Myocardial Infarction - prevention & control; Rats; Rats, Wistar
• ISSN: 0862-8408; 1802-9973
• DOI: 10.33549/physiolres.930303

The effect of chronic hypercapnia on cardioprotection induced by chronic hypoxia was investigated in adult male Wistar rats exposed to isobaric hypoxia (10 % O(2)) for three weeks. In the first experimental group, CO(2) in the chamber was fully absorbed; in the second group, its level was increased to 4.1 %. Normoxic controls were kept in atmospheric air. Anesthetized open-chest animals were subjected to 20-min LAD coronary artery occlusion and 3-h reperfusion for infarct size determination (TTC staining). Chronic hypoxia alone reduced body weight and increased hematocrit; these effects were significantly attenuated by hypercapnia. The infarct size was reduced from 61.9+/-2.2 % of the area at risk in the normoxic controls to 44.5+/-3.3 % in the hypoxic group (P<0.05). Hypercapnia blunted the infarct size-limiting effect of hypoxia (54.8+/-2.4 %; P<0.05). It is concluded that increased CO(2) levels in the inspired air suppress the development of the chronic hypoxia-induced cardioprotective mechanism, possibly by interacting with ROS signalling pathways.