The effects of erythromycin (EM) on gastrointestinal contractile activity during the interdigestive period were investigated in seven healthy subjects using an infused catheter system, and the changes in the plasma motilin concentration were also determined. Graded EM doses (0.1-1.5 mg/kg) were administered intravenously over 5 min, usually during gastric phase I. EM induced interdigestive migrating contractions (IMCs). Their induction rate was low after low doses of EM, but gradually increased as the dose increased to reach 71.4% at an EM dose of 0.375 mg/kg. Strong contractions, which were quite similar to phase III activity of the stomach but did not migrate or migrated incompletely to the duodenum, were observed at EM doses above 0.375 mg/kg. Therefore, the optimum dose of EM for inducing an IMC was established to be 0.375 mg/kg. In comparison with spontaneous IMCs, EM-induced IMCs had a significantly longer duration in the stomach and a significantly lower amplitude in the duodenum. These observations indicate that EM induced phase III activity more intensively in the stomach than in the duodenum. The plasma motilin concentration increased significantly during EM-induced IMCs, and this suggested a close relationship between this hormone and induction of the IMC. The increase in motilin levels was also observed of the strong gastric contractions which did not migrate or migrated incompletely to the duodenum. Therefore, it seems reasonable to suggest that motilin is involved in phase III activity of the stomach rather than in that of the duodenum.

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Fourteen patients with duodenal ulcers and eight healthy volunteers were examined to measure interdigestive gastroduodenal motility and plasma motilin. In order to study the effects of gastric acid on the gastroduodenal motility, 20 mg of famotidine was administered intravenously. The motility index of the gastric antrum and the duodenum, as well as the pH in the duodenal bulb were calculated. The duodenal pH was significantly lower and the gastric motility index was significantly weaker before the duodenal interdigestive migrating complex (IMC) in the ulcer patients than in the controls. Motilin levels increased before the duodenal IMC and decreased afterwards in both groups. Famotidine significantly increased the duodenal pH and the gastric motility index before the IMC, but no changes in the motilin level were noted. We conclude that duodenal ulcer patients have duodenal hyperacidity that results from increased inflow from the antrum and antral hypomotility during the gastric IMC and that these changes are normalized by the administration of famotidine. These results suggest that gastric acid inhibits antral contraction during the gastric IMC.

Mixed solutions of Ca(NO,), and (NH,),HPO, with Ca/P = 1.50 were spray-pyrolyzed at 600°C to produce p-calcium orthophosphate (P-Ca,(PO,),) powder; the spray-pyrolyzed powder was ground and then calcined at 600°C for 1 h. The best crystalline p-Ca,(PO,), powder was obtained from the solution with 1.80 mo1.L-l Ca(NO,),, 1.20 mo1-L-I (NH,),HPO,. The resulting powder was composed of primary particles with sizes of <0.5 pm. Dense P-Ca,(PO,), ceramics with a relative density of 96.1% could be fabricated by firing this compressed powder at 1070°C for 5 h.

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