Study of Drug Action and Autonomic Control of Motility
The isolated intestinal smooth muscle preparation is one of the classical preparations in physiology and pharmacology for bioassays, or the study of drug action and autonomic control of motility. This preparation is included in many "in-house" laboratory manuals of various colleges and universities around North America, and in some commercially prepared manuals deal ing with physiology and pharmacology (e.g. Nicpon-Marieb,
1981).
Basically, the method presented in this report is a modification of the original Finkleman preparation (Finkleman, 1930) for the study of the autonomic control of intestinal motility. What is different about our approach is the method of mounting the preparation and the method of stimulation of the sympathetic nerve. The classic way of mounting the piece of intestine is to suspend it vertically in a muscle bath between an aeration tube and a recording lever. The problems with this technique are
(1) stress placed on the intestine when the chamber is emptied during the process of changing solutions, and (2) difficulty in stimulating the sympathetic nerve due to the fact that the preparation is totally submerged in a physiological saline solution. We have overcome these problems by mounting the segments of gut horizontally in a shallow muscle bath. As a result, less stress is placed on the intestine during changeover of solutions, and it is easier to manipulate and to stimulate the sympathetic nerve contained within the mesentery. Also students find i t much easier to mount the preparation in the horizontal bath and are less likely to stretch the muscle preparation in the process.
With these modifications we have improved the student success rate from
50-60% to 90-100%. Large recordings of the muscle contraction, such as those shown in Appendix A, are easily obtainable using a kymograph and simple lever system. In fact, another advantage of this exercise is that it does not require
1981).
Basically, the method presented in this report is a modification of the original Finkleman preparation (Finkleman, 1930) for the study of the autonomic control of intestinal motility. What is different about our approach is the method of mounting the preparation and the method of stimulation of the sympathetic nerve. The classic way of mounting the piece of intestine is to suspend it vertically in a muscle bath between an aeration tube and a recording lever. The problems with this technique are
(1) stress placed on the intestine when the chamber is emptied during the process of changing solutions, and (2) difficulty in stimulating the sympathetic nerve due to the fact that the preparation is totally submerged in a physiological saline solution. We have overcome these problems by mounting the segments of gut horizontally in a shallow muscle bath. As a result, less stress is placed on the intestine during changeover of solutions, and it is easier to manipulate and to stimulate the sympathetic nerve contained within the mesentery. Also students find i t much easier to mount the preparation in the horizontal bath and are less likely to stretch the muscle preparation in the process.
With these modifications we have improved the student success rate from
50-60% to 90-100%. Large recordings of the muscle contraction, such as those shown in Appendix A, are easily obtainable using a kymograph and simple lever system. In fact, another advantage of this exercise is that it does not require