No abstract

We examined whether delayed gastric emptying could be produced by diabetes in dogs. Diabetes was produced by a single injection of streptozotocin (30 mg/kg i.v.), and diabetic hyperglycemia was observed from 2 to 15 months after injection. The plasma acetaminophen concentration, which is an indirect indicator of the gastric emptying rate, was delayed in 2 of 5 diabetic dogs from 15 months after the induction of diabetes. The effects of SK-951, a benzofuran derivative, on delayed gastric emptying were also examined in diabetic gastroparetic dogs in comparison with those of cisapride. SK-951 (1 mg/kg i.v.) significantly enhanced delayed gastric emptying in diabetic dogs, but cisapride (1 mg/kg i.v.) had no effect. In addition, SK-951 increased the plasma glucose levels in a manner correlated with its effect on gastric emptying. The present study suggested that SK-951 may be useful in the treatment of diabetic gastroparesis.

Renaturation of al chains from shark skin collagen (1) was measured by the increase in optical rotation and viscosity. The rotation change of the ol(1) chains became constant after 18 hr, while the viscosity increased further with time. Size exclusion chromatographic patterns of renaturation products of al(I) chain gave similar results to that of native collagen. The renaturation products remelted with rising temperature in a similar way to the melting of native collagen as judged from the rotation-temperature curve.

The gastrokinetic activity of SK-951 ((-)4-amino-N-[2-(1-azabicyclo[3.3.0]octan-5-yl)ethyl]-5-chloro-2,3-dihy dro-2-methylbenzo[b]furan-7-carboxamide hemifumarate), a benzofuran derivative with 5-hydroxytryptamine (5-HT)4-receptor agonist activity, was studied in rats and dogs. The effects of SK-951 were also investigated in a model of vagotomy-induced gastroparesis in comparison with cisapride. In rats, both SK-951 and cisapride enhanced gastric emptying of liquids (phenol red) at a dose of 1-100 mg/kg, p.o. Gastric emptying of liquid (acetaminophen) in fasted beagle dogs was enhanced significantly by SK-951 (1.0 mg/kg, i.v.), whereas the effect of cisapride (0.2-1.0 mg/kg, i.v.) was not statically significant. Similar results were found when radiopaque markers were given with standard meal to dogs with vagotomy-induced gastroparesis. The delayed gastric emptying of radiopaque markers by vagotomy was reversed by SK-951 (1.0 mg/kg, i.v.), whereas cisapride showed no effect at doses from 0.1 to 1.0 mg/kg, i.v. These results indicated that oral and intravenous administration of SK-951 accelerates gastric emptying of both liquids and solids in animal models. Thus, SK-951 may be a highly potent and useful prokinetic agent in comparison to cisapride.

SK-896 ([Leu¹³]motilin-Hse) is a new human motilin analogue synthesized by Escherichia coli using a biotechnological method. We investigated the binding of SK-896 to motilin receptors and the contractile effect of SK-896 on smooth muscle preparations isolated from the gastrointestinal tract and various regional organs in order to clarify its in vitro pharmacological profile. SK-896 inhibited the binding of ¹²⁵I-human motilin to rabbit gastroduodenal motilin receptors with the same potency as unlabeled human motilin. The IC₅₀ values of SK-896 and human motilin were 3.5 ± 1.5 and 3.1 ± 1.8 nmol/l, respectively. The K_d of human motilin was 3.0 ± 1.5 nmol/l, and the Ki of SK-896 was 3.4 ± 1.5 nmol/l. SK-896 induced contraction of smooth muscle preparations isolated from rabbit duodenum in a concentration-dependent manner. However, there was no effect of SK-896 on duodenal preparations isolated from the dog and the rat. SK-896 thus exhibited species specificity in its contractile effect. We next investigated the effect of SK-896 on various smooth muscle preparations isolated from rabbit gastrointestinal tract, trachea, bladder, gallbladder, uterus, vas deferens and artery. Results showed that SK-896 induced contraction of smooth muscle preparations isolated from gastrointestinal tract, with potencies in the order duodenum > gastric pylorus = jejunum = descending colon > ascending colon ≥ ileum. However, there was no effect of SK-896 on smooth muscle preparations from gastric fundus and other regional organs. SK-896 thus exhibited regional specificity in its contractile effect. Moreover, the effects of SK-896 on smooth muscle preparations from rabbit duodenum were the same as those of human motilin, and were not inhibited by pretreatment with tetrodotoxin and atropine but were inhibited by verapamil. These findings indicate that SK-896 has the same pharmacological profile as human motilin. They suggest that SK-896 acts on gastrointestinal smooth muscle isolated from rabbit directly and specifically.