1 In circular smooth muscle of the guinea-pig gastric fundus, transmural nerve stimulation evoked a cholinergic excitatory junction potential (ej.p.), and blockade of the ej.p. by atropine revealed a nonadrenergic non-cholinergic (NANC) inhibitory junction potential (ij.p.).2 The amplitude of the ej.p. was increased by apamin, suramin or NGnitro-L-arginine (L-NOARG), with no significant change in the membrane potential. 3 The ij.p. consisted of two components (fast and slow); apamin inhibited the former, nitroarginine inhibited the latter, and suramin inhibited both components. 4 Apamin inhibited the hyperpolarization produced by adenosine 5'-triphosphate (ATP) but not by vasoactive intestinal polypeptide (VIP). Suramin inhibited the hyperpolarization produced by VIP but not by ATP. The sodium nitroprusside (SNP)-induced hyperpolarization was not blocked by apamin or suramin. L-NOARG or tetrodotoxin did not inhibit the hyperpolarization produced by ATP, VIP or SNP. 5 The data did not support the hypothesis that ATP, VIP or nitric oxide (NO) is the main transmitter responsible for generation of the NANC ij.p. in the fundus. 6 Actions of L-NOARG suggest that endogenous NO may be involved in junctional transmission, mainly as an inhibitory modulator of cholinergic transmission.

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This case report describes a ruptured pancreaticoduodenal artery aneurysm (PDAA) causing pancreatic pseudotumour and duodenal obstruction. A 59-year-old man was referred to our hospital with a chief complaint of frequent vomiting without abdominal pain. Because a mass lesion 10 cm in diameter was palpated in the right para-umbilical region and found in the head of the pancreas on computerized tomography (CT) and ultrasonography, malignant tumour of the pancreas or tumour-forming pancreatitis was strongly suspected, and further examination was performed.Magnetic resonance imaging (MRI) results suggested subacute haematoma inside the mass. On angiography, an aneurysm 8 mm in diameter was found in the posterior superior pancreaticoduodenal artery (PSPD). Since an ultrasound-guided percutaneous needle biopsy from the solid part of the mass indicated no malignancy, the lesion was considered an inflammatory pseudotumour in the head of pancreas due to ruptured aneurysm. Bypass surgery was planned, but the tumour shrank significantly with conservative treatment. Obstruction disappeared completely without surgery 4 weeks after the first symptom.

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