Role of calcium-activated chloride channels in the regulation of pulmonary vascular tone in rats / 中国应用生理学杂志

ABSTRACT

<p><b>AIM</b>To investigate the role of calcium-activated chloride channels and the Cl- channel blockers niflumic acid (NFA) and indanyloxyacetic acid (IAA-94) in the regulation of vascular contraction induced by phenylephrine (PE).</p><p><b>METHODS</b>The PE-induced contraction in rat pulmonary artery was observed by using routine blood vascular perfusion in vitro. The fluorescence Ca2+ indicator Fura-2/AM was used to observe intracellular free Ca2+ concentration ([Ca2+]i) of rat pulmonary artery smooth muscle cells (PASMCs) which were obtained by the acute enzyme separation method (collagenase I plus papain) on NFA and IAA-94 effects on PE-induced contraction. Changes of [Ca2+]i in PASMCs were measured by spectrofluorometry.</p><p><b>RESULTS</b>The anion channel blockers NFA and IAA-94 produced inhibitory effects on PE-induced contractions in the pulmonary artery. NFA and IAA-94 negligibly affected the KCl-induced pulmonary artery contractions. PE could increase [Ca2+]i but NFA and IAA-94 negligibly affected it.</p><p><b>CONCLUSION</b>Calcium-activated chloride channels contribute to the agonist-induced pulmonary artery contractions under physiological conditions, which may be a new clue to investigate the hypoxic pulmonary vasoconstriction.</p>