Constriction of pulmonary artery by peroxide: role of Ca2+ release and PKC.
Reactive oxygen species are implicated in pulmonary hypertension and hypoxic pulmonary vasoconstriction. We examined the effects of low concentrations of peroxide on intrapulmonary arteries (IPA). IPAs from Wistar rats were mounted on a myograph for recording tension and estimating intracellular Ca2+ using Fura-PE3. Ca2+ sensitization was examined in alpha-toxin-permeabilized IPAs, and phosphorylation of MYPT-1 and MLC(20) was assayed by Western blot. Peroxide (30 microM) induced a vasoconstriction with transient and sustained components and equivalent elevations of intracellular Ca2+. The transient constriction was strongly suppressed by indomethacin, the TP-receptor antagonist SQ-29584, and the Rho kinase inhibitor Y-27632, whereas sustained constriction was unaffected. Neither vasoconstriction nor elevation of intracellular Ca2+ was affected by removal of extracellular Ca2+, whereas dantrolene suppressed the former and ryanodine abolished the latter. Peroxide-induced constriction of permeabilized IPAs was unaffected by Y-27632 but abolished by PKC inhibitors; these also suppressed constriction in intact IPAs. Peroxide caused translocation of PKCalpha, but had no significant effect on MYPT-1 or MLC(20) phosphorylation. We conclude that in IPAs peroxide causes transient release of vasoconstrictor prostanoids, but sustained constriction is associated with release of Ca2+ from ryanodine-sensitive stores and a PKC-dependent but Rho kinase- and MLC(20)-independent constrictor mechanism.
Pourmahram
Ghazaleh Esmaeil
GE
Division of Asthma, Allergy and Lung Biology, King's College London, London SE1 9RT, UK.
Snetkov
Vladimir A
VA
Shaifta
Yasin
Y
Drndarski
Svetlana
S
Knock
Greg A
GA
Aaronson
Philip I
PI
Ward
Jeremy P T
JP
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D008297:Male; D011493:Protein Kinase C / Q000378:metabolism*; D011651:Pulmonary Artery / Q000187:drug effects* / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors; D014661:Vasoconstriction / Q000187:drug effects*
D006861:Hydrogen Peroxide; D011493:Protein Kinase C; D002118:Calcium