Kaplan-Meier plot of survival over 45 days. Rats were observed for 45 days after MCT injection. MCT was uniformly fatal within 35 days. Early (preventive) treatment with VIP was followed by no mortality for 45 days, i.e., just as in control, untreated rats. Treatment with either bosentan or VIP alone, begun at 21 days, reduced mortality in MCT-treated rats by 29% (P< 0.0001). No mortality was observed during the same time period in rats that received both bosentan and VIP.