Hemorrhage is a potent stimulus for the release of vasopressin (VP), renin, and adrenocorticotropic hormone (ACTH), The goal of this study was to analyze changes in plasma VP, renin, and ACTH levels during hemorrhagic shock and resuscitation with two different solutions: hypertonic acetate dextran (HAD) and lactated Ringer's (LR) solution. Eight randomized dogs were shocked by removing 37 +/- 9 mL/kg of blood while maintaining the mean arterial pressure (MAP) at 45 +/- 5 mmHg for 1 h, Test solutions were randomized and infused as needed with the hemorrhaged blood to restore the MAP and cardiac index to baseline. Blood samples for hormone analyses were taken in baseline, shock, and resuscitation periods. For each experiment, all hormone levels increased in the postshock period and then returned to baseline values after resuscitation with both solutions. VP and renin levels rapidly returned to baseline values after resuscitation in the LR dogs compared with the HAD dogs (p < 0.05), By contrast, there was no significant difference in ACTH levels between the two solutions. High-volume infusion with LR achieves more rapid restoration than small-volume infusion with HAD for VP and renin levels. (C) 2000 Elsevier Science Inc.