We found previously that in in vitro tube form preparations of isolated intestine of streptozotocin (STZ) diabetic rats, frequency of spontaneous intraluminal pressure waves was significantly reduced in duodenum when compared with normal controls. In order to elucidate further the diabetic intestinal disorders, we examined the frequency and amplitude of spontaneous length changes and contractile responses to acetylcholine (ACh) and substance P (sP) in isolated intestinal segments of normal and experimental diabetic rats. In comparison with normal controls, we could confirm the significantly decreased frequency of spontaneous length changes in isolated longitudinal and circular muscle preparations of diabetic duodenum (1 month after STZ injection). Furthermore, amplitude of spontaneous length changes was significantly decreased in circular muscle preparations of duodenum, jejunum, and ileum but not in colon nor in longitudinal muscle preparations. Doseresponse curves revealed that both ACh and sP responses were significantly decreased in longitudinal and circular muscle preparations of diabetic duodenum, jejunum, and ileum but not in colon. Mechanisms of reduced contractility of diabetic intestinal smooth muscle in response to ACh and sP were discussed.

In order to characterize the diabetic gastrointestinal disorders such as constipation, the motor activity and the compliance of the caecum of streptozotocin diabetic rats were studied in vitro. The time course of enlargement of the caecum was also examined. Significant enlargement of the caecum was noticed in diabetic rats, 10 days after streptozotocin injection (65 mg/kg). It reached two times heavier in 30 days and three times in 90 days when compared with age-matched controls. The motor activity as studied by in vitro recording of the intraluminal pressure changes associated with spontaneous activity revealed the depression both in amplitude and frequency. The compliance was noticed to be significantly increased in the diabetic caecum as compared to age-matched controls when studied by passive Krebs solution injection. Threshold intraluminal pressure for inducing the reflex motor activity of the diabetic caecum was larger than that of the normal. These factors may contribute to the retention of content inside of the diabetic caecum.

Transit network design is an important part of urban transportation planning. The purpose of this paper is to design transit network considering transport capacity constraint. The aim of the proposed method is to maximize transport efficiency of network. Transport efficiency and routes impedance are defined based on the road restriction coefficient matrix. The k-shortest paths algorithm is applied to search efficiency route and the highest efficiency route is selected to be laid on the road network. Then, station OD matrix is updated considering station capacity. The model is illustrated with data from Siping city, China and results show that the transport efficiency of transit network is highest and meet the correlative design norms. Therefore, the model got a higher practical value.