Among the dysfunctions and pathologies associated with sepsis, the underlying molecular
mechanisms of sepsis-induced acute lung injury (ALI) are poorly understood. Endothelin
(ET)-1, a potent vasoconstrictor and pro-inflammatory peptide, is known to be involved
in the pathogenesis of ALI in a rat model of sepsis. Here, we investigated whether
landiolol hydrochloride, an ultra-short-acting β-blocker, plays a crucial role in
ameliorating and attenuating LPS-induced ALI through modulation of the ET-1 system.
Male Wistar rats at 8weeks of age were administered with either saline or lipopolysaccharide
(LPS) for three hours (3h) and some of the LPS-administered rats were continuously
treated with landiolol for 3h. ALI was induced by LPS, including levels of both circulatory
and pulmonary TNF-α and IL-6 but [PaO2] was significantly decreased. LPS also induced
a significant increase in levels of pulmonary ET-1 and ET-A receptor, but levels of
ET-B receptor, which has vasodilating effects, were remarkably diminished. Further,
LPS administration upregulated the pulmonary expression of HIF-1α. Finally, the treatment
of LPS-administered rats with landiolol for 3h ameliorated and prevented ALI, normalized
the altered levels of pulmonary ET-1 and ET-A receptors. Landiolol also induced significant
down-regulation of ET-B receptor in lung tissues in the early hours (phase) of sepsis.
However, Landiolol treatment had no effect on the up-regulated inflammatory mediators
(TNF-α, IL-6) in both plasma and lung tissues during sepsis, and expression of pulmonary
HIF-1α also remained unchanged after landiolol treatment. Collectively, these data
led us to conclude that landiolol may ameliorate sepsis-induced ALI via the pulmonary
ET system.