American journal of physiology. Heart and circulatory physiology
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Am. J. Physiol. Heart Circ. Physiol. · Aug 2008
Comparative StudyLower capacitance response and capillary fluid absorption in women to defend central blood volume in response to acute hypovolemic circulatory stress.
Acute hemorrhage is a leading cause of death in trauma, and women are more susceptible to hypovolemic circulatory stress than men. The mechanisms underlying the susceptibility are not clear, however. The aim of the present study was to examine the compensatory mechanisms to defend central blood volume during experimental hypovolemia in women and men. ⋯ FVR increased less in women during hypovolemic stress, and no association between plasma NE and FVR was seen in women (R(2) = 0.01, not significant), in contrast to men (R(2) = 0.59, P < 0.05). Women demonstrated a good initial capacitance response, but this was not maintained with time, in contrast to men [e.g., decreased by 24 +/- 4% (women) vs. 4 +/- 5% (men), LBNP of 44 mmHg, P < 0.01], and net capillary fluid absorption from tissue to blood was lower in women (0.086 +/- 0.007 vs. 0.115 +/- 0.011 ml.100 ml(-1).min(-1), P < 0.05). In conclusion, women showed impaired vasoconstriction, reduced capacitance response with time, and reduced capillary fluid absorption during acute hypovolemic circulatory stress, indicating less efficiency to defend central blood volume than men.