Effect of lipopolysaccharide from Salmonella typhi cells on blood circulation and respiration of anesthetized rats

In order to understand the processes, which cause respiration disturbance and impaired circulation during the development of a systemic inflammatory response (SIR) it is necessary to study the mechanisms which implement the cardiorespiratory effects of an increased systemic level of bacterial lipopolysaccharides (LPS). LPS obtained from various bacteria differ in the composition that determines their toxicity. The aim of the present study was to experimentally test the hypothesis that LPS isolated from bacterium Salmonella typhi (S. typhi) cells could affect reflexes involved in circulation and breathing control. Materials and Methods. The authors recorded blood pressure, pneumotachogram and diaphragm electro-myogram in acute experiments on Wistar rats (n=23, weight 200-225 g), anesthetized with urethane (1800 mg/kg, i.p.). They also calculated mean arterial pressure, heart rate, breathing capacity and respiratory minute volume. Baroreflex was tested by intravenous phenylephrine administration, which caused a dose-dependent blood pressure rise and, as a result, a reflex heart rate fall. The strength of the inspiratory inhibitory reflex (IIR) was evaluated by functional vagotomy. The values of the studied parameters were evaluated before and after intravenous administration of the physiologic saline, or the saline containing 100 pg of LPS. Parameter differences from the initial and control values were evaluated according to Mann-Whitney criterion and considered relevant at p function show_eabstract() { $('#eabstract1').hide(); $('#eabstract2').show(); $('#eabstract_expand').hide(); }