Nitric oxide modulates hypoxic pulmonary smooth muscle cell proliferation and apoptosis by regulating carbon monoxide pathway
Abstract
Aim: To explore the role of carbon monoxide (CO) in the regulation of hypoxic
pulmonary artery smooth muscle cell (PASMC) proliferation and apoptosis by
nitric oxide (NO). Methods: PASMC of Wistar rats was cultured in vitro in the
presence of a NO donor, sodium nitroprusside, or an inhibitor of heme oxygenase
(HO), zinc protoporphyrin-IX, or under both normoxic and hypoxic conditions.
Nitrite and carboxyhemoglobin in PASMC medium were detected with
spectrophotometry. The proliferating and apoptotic percentage of PASMC was
measured by flow cytometry. The expression of HO-1 mRNA in PASMC was
analyzed by fluorescent real-time quantitative PCR, and the proliferating cell nuclear
antigen and caspase-3 were examined by immunocytochemical analysis. Results:
The results showed that hypoxia suppressed NO generation from PASMC, which
promoted hypoxic PASMC proliferation and induced apoptosis. Meanwhile, hypoxia
induced HO-1 expression in PASMC and promoted CO production from
PASMC, which inhibited PASMC proliferation and regulated PASMC apoptosis.
NO upregulated the expression of HO-1 mRNA in hypoxic PASMC; NO also inhibited
proliferation and promoted apoptosis of hypoxic PASMC, possibly by regulating
the production of CO. Conclusion: The results indicated that CO could
inhibit proliferation and regulate apoptosis of PASMC, and NO inhibited proliferation
and promoted apoptosis of hypoxic PASMC, possibly by regulating the production
of CO.
Keywords:
pulmonary artery smooth muscle cell (PASMC) proliferation and apoptosis by
nitric oxide (NO). Methods: PASMC of Wistar rats was cultured in vitro in the
presence of a NO donor, sodium nitroprusside, or an inhibitor of heme oxygenase
(HO), zinc protoporphyrin-IX, or under both normoxic and hypoxic conditions.
Nitrite and carboxyhemoglobin in PASMC medium were detected with
spectrophotometry. The proliferating and apoptotic percentage of PASMC was
measured by flow cytometry. The expression of HO-1 mRNA in PASMC was
analyzed by fluorescent real-time quantitative PCR, and the proliferating cell nuclear
antigen and caspase-3 were examined by immunocytochemical analysis. Results:
The results showed that hypoxia suppressed NO generation from PASMC, which
promoted hypoxic PASMC proliferation and induced apoptosis. Meanwhile, hypoxia
induced HO-1 expression in PASMC and promoted CO production from
PASMC, which inhibited PASMC proliferation and regulated PASMC apoptosis.
NO upregulated the expression of HO-1 mRNA in hypoxic PASMC; NO also inhibited
proliferation and promoted apoptosis of hypoxic PASMC, possibly by regulating
the production of CO. Conclusion: The results indicated that CO could
inhibit proliferation and regulate apoptosis of PASMC, and NO inhibited proliferation
and promoted apoptosis of hypoxic PASMC, possibly by regulating the production
of CO.