Effects of gastrin-releasing peptide (GRP) on the mechanical activity of the human ileocaecal region in vitro.

Mechanical activity was recorded in muscle preparations isolated from the human ileocaecal region. Gastrin-releasing peptide (GRP, 10(-9)-10(-7) mol L-1) produced two types of response in the different muscle layers. Longitudinally cut strips showed a concentration-dependent increase in the rhythmic activity, whereas the circularly orientated layers generally reacted with a small decrease in tone.

Action of FMRFamide-like peptides on porcine gastrointestinal motility in vitro.

Mechanical activity was recorded in circular and longitudinal smooth muscle preparations isolated from extensive regions of the porcine gastrointestinal tract in response to the FMRFamide-like neuropeptides F8Famide and A18Famide. In all preparations, the peptides were about equipotent in producing phasic contractions or enhancing spontaneous activity. The most prominent responses were observed in jejunal longitudinal strips which were on the average 91% (+/- 4% SEM, n = 15; 10(-6) M) of the histamine (10(-5) M) responses.