Induction of lipocalin-type prostaglandin D synthase in mouse heart under hypoxemia

Hypoxemia is a common manifestation of various disorders and generates pressure overload to the heart. Here we analyzed the expression of lipocalin-type prostaglandin D synthase (L-PGDS) in the heart of C57BL/6 mice kept under normobaric hypoxia (10% O2) that generates hemodynamic stress. Northern and Western blot analyses revealed that the expression levels of L-PGDS mRNA and protein were significantly increased (>twofold) after 14 days of hypoxia, compared to the mice kept under normoxia. Immunohistochemical analysis indicated that L-PGDS was increased in the myocardium of auricles and ventricles and the pulmonary venous myocardium at 28 days of hypoxia. Moreover, using C57BL/6 mice lacking heme oxygenase-2 (HO-2−/−), a model of chronic hypoxemia, we showed that the expression level of L-PGDS protein was twofold higher in the heart than that of wild-type mouse. L-PGDS expression is induced in the myocardium under hypoxemia, which may reflect the adaptation to the hemodynamic stress.