Influence of substance P on gastrointestinal myoelectrical activity in the conscious piglet

In conscious piglets with electrodes implanted in the wall of the antrum pylori, the small intestine and the caecum, the influence of intravenous infusion of substance P (SP) (0.1 and 1 micrograms/kg/min for 2 hours) on gastrointestinal myoelectrical activity and arterial pressure was studied. SP was without significant influence on electrical activity of the antrum. However, intestinal myoelectrical activities were significantly stimulated. In the small intestine SP infusion resulted in an increase in frequency of migrating myoelectrical complexes and in irregular spiking activity, resulting in an augmentation of the integrated total activity. In the caecum SP provoked a prolongation of complexes of long spike bursts (LSB) as well as an increase in number of LSB/complex. In the studied doses SP had no significant effect on arterial pressure.