EARLY TREATMENT WITH ACTH-(1-24) IN A RAT MODEL OF HEMORRHAGIC-SHOCK PROLONGS SURVIVAL AND EXTENDS THE TIME-LIMIT FOR BLOOD REINFUSION TO BE EFFECTIVE

The ability of ACTH-(1-24) to prolong survival and to extend the deadline for effective blood reinfusion has been studied in a model of lethal hypovolemic shock in the rat. Anesthetized rats wree bled to a mean arterial pressure of 18 to 25 mm Hg and then subjected to one of the following iv treatments: a) saline; 2) ACTH-(1-24), 160 μg/kg; c) blood reinfusion; d) ACTH-(1-24), 160 μg/kg followed by blood reinfusion. All rats treated with saline 5 min after bleeding died within 0.5 h. On the other hand, the treatment with ACTH-(1-24) induced an almost complete and sustained recovery of cardiovascular and respiratory functions associated with a survival time of 44 ± 18 h, while four of six rats reinfused with the withdrawn blood were still alive 15 days later. The time-lapse between bleeding and treatment was of crucial importance, and neither ACTH-(1-24) injection nor blood reinfusion had any effect if performed 25 min after bleeding. However, treatment with ACTH-(1-24) shortly after bleeding (5 min) greatly improved the effect of a later blood reinfusion. These data indicate that ACTH-(1-24) can prolong survival and permit the time-lapse between blood loss and blood reinfusion to be extended.