New Methods to Study the Physiological Action of Medications which are Hazards to Aerospace Crew Members.
Final scientific rept.,
MINNESOTA UNIV ST PAUL DEPT OF VETERINARY PHYSIOLOGY AND PHARMACOLOGY
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The mechanism of action of drugs such as nicotine and atropine, and the influence of altered extracellular fluid environment on physiological processes, were investigated using the intestinal tract as a model organ system. A number of intestinal preparations of varying complexity were used, including isolated intestinal segments and nerve-muscle preparations in organ baths, intra-vascularly perfused colon-pelvic nerve preparations, and unanesthetized intestinal fistula animals. By studying the influence of controlled changes in the temperature, osmolarity, gas tensions, ionic composition, and drug content of the extracellular fluid on motor responses of intestine to acetylcholine, nicotine, acute potassium deprivation, and extrinsic nerve stimulation, it was established that nicotines predominant excitatory effect on motor function of isolated intestine differs in mechanism from the effect of acetylcholine or extrinsic motor nerve stimulation, and most closely resembles in mechanism the effect of acture potassium deprivation. Atropine was demonstrated to have significant effects on motor function of isolated intestine which were unrelated to cholinergic blockade and which were dramatically influenced by changes in extracellular fluid composition that did not affect atrophines cholinergic blocking action. Author