Experiments were conducted in vitro to determine whether arterial infusion of the C-terminal octapeptide of cholecystokinin (CCK-8) into cat jejunal segments could elicit propulsive behavior when a segment must do hydrostatic work to expel fluid. Oral and aboral ends of jejunal segments, 17 cm in length, were connected to a propulsion evaluation system that imposed input-output conditions of constant capacitance and negligible resistance. Infusion of 1 X 10(-10) to 3 X 10(-9) M CCK-8 produced an initial simultaneous ejection of approximately equal volumes of fluid from both ends of the segments. This reduction in luminal volume lasted for approximately 4 min. Concurrent with this initial reduction in luminal volume were phasic ejections of fluid that often did not occur simultaneously or with equal magnitude from both ends of a segment. This pattern persisted throughout the period of CCK-8 infusion. Arterial infusion of atropine sulfate (10(-6) M) or hexamethonium sulfate (2.8 X 10(-7) M) prevented the induction of propulsive behavior by CCK-8. These results indicate that arterial infusion of CCK-8 can induce a specific pattern of jejunal propulsive behavior by triggering neural activity in the enteric nervous system and that CCK-8 may have a physiological role in regulating propulsion.
Animals Atropine