Autonomic dysfunction in experimental sepsis induced by cecal ligation and puncture

A systemic inflammatory response to infection characterizes sepsis which associated to refractory hypotension, turns into severe sepsis. Our aim was to evaluate hormonal and cardiovascular alterations after experimental sepsis induced by cecal ligation and puncture (CLP). Male Wistar rats (200-250 g) were submitted to CLP or sham operation. The animals were decapitated at 0, 2, 4, 6 and 8 h after surgery for collection of blood samples for plasma osmolality, sodium and vasopressin (AVP) measurements. The mean arterial pressure (MAP) and heart rate (HR) were recorded 1 h before and to each 1 h during 5hs after surgery. The spontaneous baroreflex sensitivity and spectral analysis of HR and MAP variability were analyzed after recording. The plasma osmolality and sodium did not show any alterations compared to the sham group. MAP decreased from 3 h (85 vs.103 mm Hg, P<0.05) to 5 h in the CLP group (76 vs.106 mm Hg, P<0.05). This was accompanied by an increase in HR. The AVP plasma level was elevated at 4 h (6.0+/-1.1 vs. 1.1+/-0.2 pg/mL, P<0.05) and returned to basal levels at 8 h after CLP (2.3+/-0.5 vs. 1.9+/-0.2 pg/mL, P>0.05). A reduction in baroreflex sensitivity occurred 1 h after injury. The CLP group showed a reduction in overall variability, low-frequency power, and low/high-frequency ratio of HR and low-frequency power of MAP. The data suggest an impairment of autonomic control of the heart and vessels during polymicrobial sepsis. This reduction in autonomic nervous system activity causes the impairment of baroreflex that in turn may contribute to the reduction of vasopressin plasma levels in the late phase of severe sepsis.