Effects of niflumic acid on the pulmonary vasoconstriction of human in acute hypoxia conditions

Aim To investigate the effects of nifiumic acid(NFA),an inhibitor of calcium-activated chloride(ClCa)channels,on pulmonary vasoconstriction of human in acute hypoxic conditions.Methods Acute hypoxia-induced contraction was observed in human pulmonary artery by using routine blood vascular perfusion in vitro;the fluorescence Ca2+ indicator Fura-2/AM was used to observe intracellular free Ca2+ concentration(i) in human pulmonary artery smooth muscle cells(PASMCs)through putting into ClCa channel blockers NFA and indaryloxyacetic acid(IAA-94)in normal(37℃,5% CO2,21% O2,74% N2)and acute hypoxic(37℃,5% CO2,2% O2,93% N2)conditions.Results ① In acute hypoxic condition,i was increased:in normoxic condition,i was(103.26±4.72)nmol·L-1,and in hypoxic condition,i was(253.89±9.82)nmol·L-1(P0.01);The NFA and IAA-94 decreasedi from(253.89±9.82)nmol·L-1 to(107.18±14.99)nmol·L-1(P0.01).② Acute hypoxia evoked pulmonary artery contractions from(4.54±0.52)g·g-1 to(49.51±1.30)g·g-1(P0.01);The NFA and IAA-94 inhibited hypoxia-evoked contractions in the pulmonary artery from(49.51±1.30)g·g-1 to(4.50±0.40)g·g-1(P0.01).Conclusions NFA can inhibit the contraction of human pulmonary artery in acute hypoxic condition,which may result from the inhibition of activity ClCa channels.