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Hypertonic saline induces prostacyclin production via extracellular signal-regulated kinase (ERK) activation
1Department of Surgery, University of Washington, 1959 NE Pacific Street, Seattle, Washington 98195-6410, USA.
Background:
Hypertonic saline (HTS) resuscitation exerts protective effects in reperfusion injury including a decrease in pulmonary vascular resistance and an increase in microvascular perfusion and cerebral blood flow; however, the mediators of these effects are unknown. Prostacyclin (PGI2) is a paracrine mediator with two main effects, vasodilation and inhibition of platelet aggregation. We hypothesized that HTS may induce PGI2 production by endothelial cells.
Methods:
Human umbilical vein endothelial cells (HUVECs) were treated with varying concentrations of NaCl. After 12 h of incubation, the supernatant was assayed for 6-keto-prostaglandin F1, a stable metabolite of PGI2, by ELISA. Phospho-specific ERK-1 and ERK-2 mitogen-activated protein kinase (MAPK) antibody, which recognizes only activated ERK, was used to determine ERK activation status by Western blotting.
Results:
Addition of 20-100 mM NaCl or endotoxin [lipopolysaccharide (LPS)] induced PGI2 production by HUVECs. HTS and LPS induced ERK-1 and ERK-2 activation. PGI2 production was inhibited when the HUVECs were pretreated with PD 98059, a specific inhibitor of ERK phosphorylation.
Conclusion:
These data suggest that HTS induces PGI2 production in HUVECs. In addition, HTS and LPS induce activation of ERK which is required for PGI2 production. HTS resuscitation may improve microvascular circulation and decrease reperfusion injury via induction of PGI2 production by endothelial cells.