Model of septic shock induced by live E. coli (O18) in a laboratory rat

Abstract

This study was concerned with the development of induced septic shock in a laboratory rat using a series of measurements including body temperature, heart and respiratory rates, haematocrit value, red and white blood cell counts, differential leukocyte count, haemoglobin value, glycaemia, analysis of arterial blood gases, and serum levels of interleukin 6 (IL-6) during the first five hours. A total of 12 specific pathogen free (SPF) laboratory rats were used for the study. Septic shock was induced under general anaesthesia by introducing live <I>E. coli</I> (O18) into the jugular vein in the dose of 1 × 10<sup>9</sup> per 100 g of body weight (group SESH). Clinical measurements and blood collection from <I>a. carotis</I> were performed just prior to, and then 1.5 and 5 h after the administration of <I>E. coli.</I> The control group (C) contained 9 SPF laboratory rats which received physiological saline only, at the same volume into the jugular vein, and blood collection followed according to the same scheme as above described for group SESH. The results of the experiment showed that changes in clinical, haematological and biochemical parameters could be detected as early as 1.5 hours after induction. These changes correspond with the activation of an inflammatory reaction and the development of metabolic acidosis. They are accompanied by a considerable rise in IL-6 already 1.5 h after the application of live <I>E. coli</I> and after 5 h the levels exceeded 2 000 pg/ml in all experimental animals. Our results clearly document the importance of IL-6 for the early detection of developing septic shock and of some less specific but routinely determined parameters such as white blood cell count and base excess.