Physiological and pathophysiological aspects of heart regulation in a model of experimental inflammation in rats

Abstract

Aim of research – to study the effect of LPS-induced inflammation on the functional state and regulation of the heart rate in rats.

Materials and methods. The study was carried out in adults of male Wistar rats in accordance with bioethical standards. To stimulate acute inflammation, rats of the experimental group (n = 12) were once injected with a solution of Salmonella typhi lipopolysaccharide (LPS; intraperitoneal; 0,1 mg/kg).  The control group rats (n = 8) were administered saline solution injections following a similar method. Changes in hemodynamic parameters associated with the development of acute inflammation (number of individual leukocyte types; concentration of C-reactive protein; leukocyte intoxication index; systemic inflammation index) were assessed. Blood circulation parameters were recorded in non-anesthetized rats using the Coda Monitor device. The heart regulation under inflammation conditions was assessed by changes in heart rate under the influence of norepinephrine solutions (intraperitoneal; 0,3 μg/kg). The results of the research were processed using SigmaStat 12.5. Results were considered statistically significant at p < 0,05.

Results. The administration of Salmonella typhi LPS led to the resulted of characteristic signs of inflammation: leukocytosis, ensured by an increase in the level of neutrophils; increased indices of systemic inflammation and endotoxemia; increase in C-reactive protein. Under inflammation conditions, the systolic, diastolic and mean blood pressure decreased, and the volumetric flow rate in the tail vessel decreased. These hemodynamic changes occur due to an increase in heart rate. The LPS-induced model of inflammation had a modulating effect on the mechanisms of cardiac regulation: there has been a decrease in the effectiveness of reflex bradycardia in increasing blood pressure due to the administration of norepinephrine.

Conclusion. Administration of Salmonella typhi LPS has a modulating effect on various cardiac activity and hemodynamic indicators. The dominant reaction to bacterial endotoxin is reduced blood pressure and increased tachycardia. Under the conditions of the inflammation model LPS-induced, the efficiency of baroreflex regulation of the heart decreased.