Organ Blood Flow and the Central Hemodynamic Response are Better Preserved in Female, As Opposed to the Male Rats, After Trauma-Hemorrhagic Shock

Abstract

The objective of this study was to test the hypotheses that the better resistance of proestrus female than male rats to trauma-hemorrhagic shock (T/HS)-induced gut and other organ injury, and it is associated with better preservation of central hemodynamics and organ blood flow including blood flow to the intestine. Male and female proestrus rats were subjected to T/HS (laparotomy and 90 minutes of shock at a mean arterial blood pressure of 35-40 mm Hg) or trauma sham-shock after that cardiac index, systemic vascular resistance, and organ blood flow was measured 15 minutes before the end of the shock period and at 15 minutes, 60 minutes, and 180 minutes after volume resuscitation. The hemodynamic response to T/HS was better preserved during the shock period in the female than male rats and this was manifest as better maintenance of central hemodynamics (cardiac output and systemic vascular resistance) and intestinal as well as other organ microcirculatory blood flow. Cardiac output had returned toward normal at 15 minutes after volume resuscitation in both the male and female rats, however only in the female rats was there a consistent increase in organ blood flow after volume resuscitation. In contrast, in the male T/HS rats, the level of organ blood flow, especially to the splanchnic organs, remained similar to that observed during the shock period. These results indicate that the greater resistance of female than male rats to gut and other organ injury after T/HS is associated with better preservation of central hemodynamics and organ blood flow during the shock and postshock periods.