[Calcium-activated chloride channels are involved in two-phase hypoxic pulmonary vasoconstriction in rat pulmonary arteries].
The aim of the present study was to investigate the roles of calcium-activated chloride channels (Cl(Ca)) in the two-phase hypoxic pulmonary vasoconstriction (HPV). The second pulmonary artery branches were dissected from male Sprague-Dawley rats, and the changes in vascular tone were measured by using routine blood vascular perfusion in vitro. The result showed that, under normoxic conditions, Cl(Ca) inhibitors (NFA and IAA-94) significantly relaxed second pulmonary artery contracted by norepinephrine (P < 0.01), but merely had effects on KCl-induced second pulmonary artery contractions. A biphasic contraction response was induced in second pulmonary artery ring pre-contracted with norepinephrine exposed to hypoxic conditions for at least one hour, but no biphasic contraction was observed in pulmonary rings pre-contracted with KCl. NFA and IAA-94 significantly attenuated phase II sustained hypoxic contraction (P < 0.01), and also attenuated phase I vasodilation, but had little effect on phase I contraction. These results suggest that Cl(Ca) is an important component forming phase II contraction in secondary pulmonary artery, but not involved in phase I contraction.
Department of Pathophysiology; Institute of Ischemia-reperfusion Injury, Wenzhou Medical University, Wenzhou 325035, China; Department of Anesthesiology, The Sixth People's Hospital of Shanghai, Shanghai 200233, China. wzwwt@tom.com.
Lei
L
Ying
Hai-Xia
HX
Yao
Lin-Jing
LJ
Huang
Ying-Chun
YC
Ma
Jin-Bo
JB
He
Dan
D
Chen
Hai-E
HE
Chen
Yang
Y
Wang
Wan-Tie
WT
Wang
D000818:Animals; D018118:Chloride Channels / Q000502:physiology*; D006016:Glycolates / Q000494:pharmacology; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D011651:Pulmonary Artery / Q000503:physiopathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014661:Vasoconstriction; D014664:Vasodilation
D018118:Chloride Channels; D006016:Glycolates; C015765:MK 473; D009638:Norepinephrine