Rat aortic smooth muscle cells were used as a model system to characterize the binding properties of [3H]SK&F 108566, an angiotensin type-1 (AT1) receptor antagonist. The binding was specific, saturable and reversible. The association and dissociation rates of [3H]SK&F 108566 binding to smooth muscle cells were monophasic and Scatchard analysis of equilibrium binding data yielded a linear plot indicating a homogenous population of binding sites. The maximum binding (Bmax) and apparent dissociation constant (Kd) were 22,000 +/- 6000 sites/cell and 0.83 +/- 0.08nM respectively. The pharmacological specificity of [3H]SK&F 108566 binding to smooth muscle cells is consistent with that observed for AT1 and confirms AT1 receptor specificity of this radioligand. High affinity binding was observed in membranes prepared from bovine adrenal cortex, rat liver and rat kidney glomeruli. COS cells transfected with cDNA encoding human AT1 angiotensin II receptors also displayed high affinity binding site for [3H]SK&F 108566. No specific binding could be detected on membranes prepared from bovine cerebellum, a tissue rich in the angiotensin type-2 (AT2) receptor. These observations indicate that [3H]SK&F 108566 binds to sites which have pharmacological characteristics of angiotensin II AT1 subtype receptors and can be used as a subtype-selective radioligand to characterize AII receptors in various systems.

Four cases of foreign bodies in the duodenum were treated using a flexible fibre-optic panendoscope. All the patients were boys and eight months to four years of age. The ingested foreign materials were an injection needle, a marking pin, a hairpin and a curtain hook. Endoscopic extraction was attempted, because the ingested objects might cause perforation or obstruction of the gastrointestinal tract. Until recently, they had to be carefully watched or prophylactic operation suggested. Under general anaesthesia, duodenal endoscopy was easily performed and extraction of foreign bodies was not found to be difficult during infancy. This is considered to be a safer and less hazardous way than careful watching or prophylactic operation.