Guinea Pig Ileum

A computer simulation program to teach the effects of drugs and electrical stimulation on the enteric nervous system.

This program simulates an isolated preparation of the guinea pig ileum, a smooth muscle preparation exhibiting little spontaneous contractile activity, which is extensively used for pharmacological studies. Its aim is to enable the exploration of the effects of drugs and electrical stimulation on the release of, and response to, neurotransmitters in the enteric nervous system. Simulated responses are derived from a model which presents the contractile response of the ileum both to added drugs and to transmural electrical stimulation. Learning is through exploration and the program places at the disposal of the user a range of DRUGS (acetylcholine, histamine, clonidine, morphine, naloxone, phentolamine, atropine, mepyramine) which may be added alone or in combination to the organ bath in a range of DOSES, and an electrical STIMULATOR. A 'magic' WASH facility instantly removes all traces of added drugs and greatly speeds up the process of data collection compared to the real experiment. Simulated contractions of the gut are presented on a scrolling display comparable to that of a chart recorder. Students may take measurements directly from the monitor.

The program has four sections: Introduction uses text, high quality graphics and quizzes to enable students to learn the appropriate structures in the small intestine and the pharmacological basis of how motility is controlled. Methods describes the apparatus and the experimental protocols. A Pretest section tests the students understanding of the information presented in the introduction and methods sections. Experiments is the main section and allows students to simulate performing several experiments:

• action of drugs (acetylcholine, histamine, atropine and mepyramine);
• dose response curve for acetylcholine and determination of ED₅₀;
• dose response curve for acetylcholine in the presence of atropine and determination of ED₅₀;
• effects of low frequency transmural electrical stimulation (10V, 0.1 Hz) and the action of drugs (atropine, phentolamine, naloxone, clonidine, morphine)
• effects of high-frequency transmural electrical stimulation (10V, 10Hz) and the action of naloxone and phentolamine.