title: β-Adrenergic signaling in rat heart is similarly affected by continuous and intermittent normobaric hypoxia.
abstract: Chronic hypoxia may produce a cardioprotective phenotype characterized by increased resistance to ischemia-reperfusion injury. Nevertheless, the molecular basis of cardioprotective effects of hypoxia is still not quite clear. The present study investigated the consequences of a 3-week adaptation to cardioprotective (CNH, continuous normobaric hypoxia) and nonprotective (INH, intermittent normobaric hypoxia; 23 h/day hypoxia followed by 1 h/day reoxygenation) regimen of hypoxia on β-adrenergic signaling in the rat myocardium. Both regimens of hypoxia lowered body weight and led to marked right ventricular (RV) hypertrophy, which was accompanied by 25% loss of β1-adrenergic receptors (β1-ARs) in the RV. No significant changes were found in β-ARs in left ventricular (LV) preparations from animals adapted to hypoxia. Although adenylyl cyclase (AC) activity stimulated through the G proteins was decreased in the RV and increased in the LV after exposure to hypoxia, there were no significant changes in the expression of the dominant myocardial AC 5/6 isoforms and the stimulatory G proteins. These data suggest that chronic normobaric hypoxia may strongly affect myocardial β-adrenergic signaling but adaptation to cardioprotective and nonprotective regimens of hypoxia does not cause notably diverse changes.
authors.affiliation: Department of Physiology, Faculty of Science, Charles University in Prague, Prague, Czech Republic. klara.hahnova@natur.cuni.cz.
authors.forename: Klara
authors.initials: K
authors.lastname: Hahnova
authors.forename: Dita
authors.initials: D
authors.lastname: Kasparova
authors.forename: Jitka
authors.initials: J
authors.lastname: Zurmanova
authors.forename: Jan
authors.initials: J
authors.lastname: Neckar
authors.forename: Frantisek
authors.initials: F
authors.lastname: Kolar
authors.forename: Jiri
authors.initials: J
authors.lastname: Novotny
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D011943:Receptors, Adrenergic, beta; D010100:Oxygen