Administration of ATP-MgCl2after Trauma–;Hemorrhage and Resuscitation Restores the Depressed Cardiac Performance

Abstract

Although adenosine triphosphate (ATP)-MgCl2has been shown to improve cardiac performance under normal and postischemic conditions, it is not known whether this agent has any salutary effects on cardiac performance following trauma–;hemorrhage and crystalloid resuscitation. To determine this, rats underwent laparotomy (i.e., trauma induction) and were bled to and maintained at a mean arterial pressure of 40 mm Hg until 40% of the maximum shed blood volume was returned in the form of Ringer's lactate. The animals were then resuscitated with four times the volume of shed blood using Ringer's lactate over 60 min and received either ATP-MgCl2(50 μmole/kg body wt) in 1 ml volume or an equivalent volume of normal saline intravenously over 95 min. MaximumdP/dtduring contraction as well as relaxation (±dP/dtmax) and ventricular peak systolic pressure (VPSP) were determined 15 min prior to the end of resuscitation and every 30 min thereafter for 4 hr after the completion of resuscitation. The results indicate that both −dP/dtmaxand +dP/dtmaxdecreased significantly beginning at 0 and 2 hr after the completion of resuscitation, respectively, and remained depressed throughout the duration of the study in saline-treated animals. In addition, VPSP was significantly depressed at 2–;4 hr after resuscitation. Treatment with ATP-MgCl2, however, restored these parameters. Moreover, the depressed heart rate was also restored following ATP-MgCl2administration. Since ATP-MgCl2restores various left ventricular performance parameters, this agent appears to be a promising adjunct for improving cardiac function after trauma and hemorrhage, even in the absence of blood resuscitation.