[An experimental study on the change in cardiac sympathetic neuroelectrophysiology in severely scalded rats during...

To investigate the mechanism and the rule of the change in cardiac sympathetic neuroelectrophysiology in severely scalded rats during early postburn stage, so as to explore the relationship between the change and postburn severe cardiac injury.

Forty-four Sprague-Dawley rats were randomly divided into normal (n = 6), sham injury (n = 8) and scalded (n = 20) groups. The rats in scalded group were inflicted by 30% TBSA III degree burn on the backs. The electric discharge activity of cardiac sympathetic nerve was observed and recorded by neuroelectrophysiological technique. The changes in ECG and myocardial mechanic indices were simultaneously observed.

The activity of efferent cardiac sympathetic nerve increased immediately after scalding, but that of the afferent nerve increased obviously after about 90s incubation period. The activity of efferent nerve further increased after the increase of afferent activity, and this increase in both efferent and afferent nerves lasted for about 3 hours and decreased evidently thereafter. The change of afferent nerve was earlier than that of efferent nerve. The average electric discharge activity of cardiac sympathetic nerve increased with obvious fluctuation, which exhibited intermittent burst pattern at 1 PBH in some rats, in which frequent ventricular extrasystole appeared accompanying with the simultaneous increase in electric discharge burst in 4 rats. The postburn LVDP and +/- dp/dtmax in rats decreased significantly.

The activities of both efferent and afferent cardiac sympathetic nerve increased dramatically in the early postburn stage. The change in efferent nerve activity could be affected to some degree by that of afferent nerve. This implied that the increase of the neuroelectrophysiological activity of cardiac sympathetic nerve might be one of the causes of early severe postburn cardiac injury.