Effect of chronic hypoxia on agonist-induced tone and calcium signaling in rat pulmonary artery |
| |
Authors: | Bonnet S Belus A Hyvelin J M Roux E Marthan R Savineau J P |
| |
Affiliation: | Laboratoire de Physiologie Cellulaire Respiratoire, Institut National de la Santé et de la Recherche Médicale (Equipe Mixte 9937), Université Bordeaux 2, 33076 Bordeaux, France. |
| |
Abstract: | The effect of chronic hypoxia (CH) for 14 days on Ca2+ signaling and contraction induced by agonists in the rat main pulmonary artery (MPA) was investigated. In MPA myocytes obtained from control (normoxic) rats, endothelin (ET)-1, angiotensin II (ANG II), and ATP induced oscillations in intracellular Ca2+ concentration ([Ca2+]i) in 85-90% of cells, whereas they disappeared in myocytes from chronically hypoxic rats together with a decrease in the percentage of responding cells. However, both the amount of mobilized Ca2+ and the sources of Ca2+ implicated in the agonist-induced response were not changed. Analysis of the transient caffeine-induced [Ca2+]i response revealed that recovery of the resting [Ca2+]i value was delayed in myocytes from chronically hypoxic rats. The maximal contraction induced by ET-1 or ANG II in MPA rings from chronically hypoxic rats was decreased by 30% compared with control values. Moreover, the D-600- and thapsigargin-resistant component of contraction was decreased by 40% in chronically hypoxic rats. These data indicate that CH alters pulmonary arterial reactivity as a consequence of an effect on both Ca2+ signaling and Ca2+ sensitivity of the contractile apparatus. A Ca2+ reuptake mechanism appears as a CH-sensitive phenomenon that may account for the main effect of CH on Ca2+ signaling. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|