Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P61278 (somatostatin)
 22,083 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The study provides pharmacokinetic data for exogenous synthetic and endogenous natural motilin in man. Synthetic 13-norleucine-motilin was infused into 6 healthy volunteers at a dose of 0.6 and 2.4 (pmoles per kg) per min over 60 min and plasma motilin was measured by radioimmunoassay. During the infusions mean plasma levels of 124.8 +/- 14.8 and 360 +/- 19.6 pmoles per liter, respectively, were achieved. Disappearance half-time on stopping the infusion was 4.36 min. The apparent volume of distribution was calculated to be 49.4 +/- 3.3 ml per kg, and the metabolic clearance rate was 7.8 +/- 0.5 (ml per kg) per min. To measure the decay of endogenous motilin somatostatin was used in the same 6 subjects. A bolus of 100 mug and a subsequent 15-min infusion of 15 mug per min of somatostatin suppressed the fasting motilin level by 50%. The disappearance half-time was 4.56 min. It is concluded that both synthetic and endogenous motilin are eliminated by first order kinetics with very similar half-times. Our data also suggest that the previously reported motilin infusions at these dose levels gave plasma concentrations within the physiological range and that the effects noted may thus have reflected the physiological actions of motilin.
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PMID:Pharmacokinetics of motilin in man. 83 89

A bland procedure, conducted in ice, is described for the extraction with HCl of smooth-muscle-contracting substances from plexus-containing ileal longitudinal muscle (l.m.) sheets obtained mainly from rabbits and some guinea-pigs. The spasmogenic activity in rabbit extracts was distinguished from acetylcholine, histamine and 5-hydroxytryptamine by antagonists; and from prostaglandins, by its insolubility in ether at acid pH and by pretreatment of the animals with indomethacin. The fact that it contracts the separated l.m. of the guinea-pig ileum, whether plexus-containing or plexus-free, and in atropine distinguishes it also from methionine-enkephalin, somatostatin, 13-norleucine motilin, bombesin, and cholecystokinin octapeptide (CCK8). This activity was partially purified, first by several partitions with ether at pH 1.4-2.2 and then by treatment at pH 4.5-5 with lead acetate. The virtual absence of ATP was confirmed by the firefly bioluminescence technique. The guinea-pig-ileum-contracting component in the partially purified extracts was destroyed by pepsin, chymotrypsin and DPCC-treated trypsin, indicating its peptide nature and distinguishing it from oxytocin, vasopressin, bradykinin, etc. In parallel assays the partially purified rabbit extracts were considerably more active than Substance P on jird or rat ascending colons than on the guinea-pig l.m., suggesting the presence of a second spasmogenic component in the extracts. In guinea-pig extracts the partially purified activity was 8-16 times greater when plexus-containing than when plexus-free, pointing to Auerbach's plexus as the source of the activity.
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PMID:Extraction and partial purification of spasmogenic substances in Auerbach's plexus. 242 21

Motilin receptors in rabbit antral and duodenal smooth muscle tissue were characterized by direct binding technique using 125I-labeled porcine motilin as a tracer ligand. Binding at 30 degrees C was maximal at 90 min, was saturable and partially reversible. Displacement studies with natural porcine motilin, synthetic leucine-motilin or norleucine-motilin indicated a dissociation constant (Kd) of 1.1 +/- 0.3 nM and a maximal binding capacity (Bmax) of 42 +/- 10 fmol/mg protein. Binding was unaffected by glucagon, pancreatic polypeptide and somatostatin, but substance P interfered via an unknown mechanism. By density gradient centrifugation motilin receptors were shown to be present in plasma membranes. Binding could only be demonstrated in preparations from antrum and upper duodenum. These observations provide evidence for a localized target region for motilin in the gastrointestinal tract, and for a direct interaction of motilin with gastrointestinal smooth muscle tissue.
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PMID:Motilin receptors in rabbit stomach and small intestine. 378 36