Choline acetyltransferase activity parallels the pressure gradient in the feline pharyngo-esophageal region.

Pressures generated by the pharyngeal constrictor muscles and proximal esophagus involve acetylcholine-induced muscle contractions. We hypothesized that the pharyngo-esophageal pressure gradient is related to choline acetyltransferase activity. In nine anesthetized cats, hypopharyngeal pressure and proximal esophageal pressure were recorded with a solid state transducer assembly. Enzymatic activities in the thyropharyngeus, cricopharyngeus, and proximal esophageal muscles were measured. Hypopharyngeal pressure was higher than the proximal esophagus (p < 0.01), and choline acetyltransferase activity was higher in the cricopharyngeus compared to the proximal esophagus ( p < 0.05). The pressure gradient between the hypopharynx and proximal esophagus may be influenced by the activity of choline acetyltransferase.

Gut hormone release in patients after spinal cord injury.

Gastrointestinal disorders including abdominal pain, abdominal distention, ileus, and constipation are common after spinal cord injury. In physiologic studies of patients with spinal cord injury, slow gastric emptying, ileal dilation, and abnormal rectosigmoid motility have been found. However, it is not yet known whether abnormal gut hormone release is important in the development of these abnormalities. In healthy volunteers, there are postprandial increases in plasma peptide YY and motilin levels, which appear related to neural mechanisms. We hypothesized that abdominal sympathetic pathways provide tonic inhibition of peptide YY and motilin release and that postprandial increases in these gut hormones are mediated through spinal pathways. Fasting serum was obtained from normal volunteers, paraplegic patients, and tetraplegic patients. In studies in which patients were fed, serum was obtained from normal volunteers, paraplegic patients, and tetraplegic patients before and at 30-min intervals after a 280 kcal meal. Serum motilin and peptide YY levels were measured by radioimmunoassays. In fasting studies, there was a trend (P = 0.23) toward increased fasting serum motilin in paraplegic patients, and this result did not support tonic inhibition of motilin release. Fasting peptide YY levels were not increased in spinal cord injury patients, which did not support tonic inhibition of peptide YY release. In fed studies, there were strong trends toward postprandial increases in serum peptide YY in volunteers and paraplegic patients and a significant postprandial rise in serum peptide YY in tetraplegic patients (P = 0.04). This was evidence against involvement of spinal pathways in postprandial release of peptide YY.(ABSTRACT TRUNCATED AT 250 WORDS)

Muscarinic cholinergic receptor density following small intestinal transplantation in rats.

After small intestinal transplantation, intestinal isografts can organize migrating myoelectric complexes, and we have shown that migrating myoelectric complex frequency in the fasted state was reduced compared with controls after transplantation of the distal 50% of small intestine. We hypothesized that changes in motor activity after transplantation were related to alteration of cholinergic nerve activity or receptor density. With use of standard microsurgical techniques, the distal 50% of small intestine was orthotopically transplanted in a Lewis-to-Lewis donor-recipient combination. Resection controls were prepared by resecting the proximal 50% of small intestine, and sham controls were prepared by performing a sham laparotomy. Two months after surgery, small intestine was harvested. Choline acetyltransferase activity among the three groups was similar, suggesting that intrinsic cholinergic nerves remained intact. There was a strong trend toward decreased acetylcholinesterase activity [analysis of variance (ANOVA), P = 0.16] after transplantation, consistent with loss of extrinsic vagal nerve fibers. There were no differences in histochemical distribution of acetylcholinesterase among these groups. Muscarinic receptor density, as determined by binding to [N-methyl-3H]scopolamine, was decreased after transplantation (ANOVA, P = 0.02). There was a trend toward decreased receptor density in animals with resected small intestine. Surgical interruption of intrinsic nerve pathways rather than ischemia or extrinsic denervation might be the mechanism for diminished receptor density after transplantation, and reduced small bowel motor activity may be related to decreased density of muscarinic cholinergic receptors.