Hypertonic saline induces prostacyclin production via extracellular signal-regulated kinase (ERK) activation

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 dow; however, the mediators of these effects are unknown. Prostacyclin (PGI(2)) is a paracrine mediator with two main effects, vasodilation and inhibition of platelet aggregation. We hypothesized that HTS may induce PGI(2) 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 F-1, a stable metabolite of PGI(2), 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 PGI(2) production by HUVECs. HTS and LPS induced ERK-1 and ERK-2 activation. PGI(2) production was inhibited when the HUVECs were pretreated with PD 98059, a specific inhibitor of ERK phosphorylation. Conclusion. These data suggest that HTS induces PGI(2) production in HUVECs. In addition, HTS and LPS induce activation of ERK which is required for PGI(2) production. HTS resuscitation may improve microvascular circulation and decrease reperfusion injury via induction of PGI(2) production by endothelial cells. (C) 1999 Academic Press.