Different Responses Of Muscle Fibers From The Human Gastroesophageal Junction To Different Neurotransmitters

From August 24 to December 27, 2000, the responses of human sling and clasp fibers to acetylcholine (Ach), dopamine (DA), phenylephrine, and (-)-isoprenaline were studied. Circular muscle fibers of the esophagus and the gastric fundus were also tested as controls. The specimens of esophagogastric junction were from 18 patients who were operated on for esophageal cancer. We found that both Ach and phenylephrine increased the tension of the 4 strips, the values in Ach group being 3-4 times greater than in phenylephrine group.However, (-)-isoprenaline decreased the tension of muscle strips, The tension of the stripes were reduced with DA at lower concentration, and then increased gradually with the rising of concentration. The sensitivities and maximum responses to each important agent were different in the 4 muscle fibers. This implies that the densities and subtypes of the neurocepters are different between the 4 muscle fibers.