Motor effects of graded doses of pentagastrin on the gut of the anesthetized dog.

Gastrointestinal motor activity of the anesthetized dog was assessed by strain gage force transducers on longitudinal and transverse muscle of the gastric body and antrum, duodenum, jejunum, ileum, and colon. Dose-dependent effects of pentagastrin (1-8192 ng/kg, i.v.) were only seen on the stomach: increases in gastric body tone, antral contractile force and contractile frequency of the gastric phasic activity. Body tone and antral force were more sensitive to pentagastrin than was contractile frequency. Supra-maximal doses and repetition of the dose-response protocol gave smaller increments for body tone and antral force, while the increase in contractile frequency remained unaffected. The different responses to pentagastrin of force and frequency indicate that pentagastrin acts on 2 different receptor-effector systems.