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

Clearance of cyclic somatostatin (SRIF) from a plasma-free recirculating medium containing human erythrocytes and a bovine albumin fraction was measured with site-specific N-terminal (sheep B) and central core-directed (R101) radioimmunoassays during perfusion of the isolated rat liver (3-4 g). With the N-terminal radioimmunoassay (RIA), the t 1/2, hepatic clearance, and extraction of somatostatinlike immunoreactivity (SLI) were 20.9 +/- 2.0 (SE) min, 2.82 +/- 0.27 ml/min, and 35.2 +/- 3.4%. Corresponding values for the centrally directed assay were 51.0 +/- 6.3 min, 1.16 +/- 0.14 ml/min, and 14.4 +/- 1.8%. Clearances of immunoprecipitable 125I-Tyr-SRIF and [125I-Tyr11]SRIF were 6.56 and 1.06 ml/min, respectively, and were not saturable by 1 microM Tyr-SRIF and SRIF, respectively. SRIF (1.26 +/- 0.09 nM) and SRIF-28 (1.34 +/- 0.14 nM) clearances determined by R101 RIA were similar. After SRIF-28 perfusion, high-performance liquid chromatographic analysis of SLI showed 86% to be retained with the SRIF-28 peak and 14% with the SRIF peak, suggesting no major conversion of SRIF-28 to SRIF. Des-(Ala1,Gly2)-N3-Ac-SRIF and dihydrosomatostatin were cleared more rapidly than SRIF. Clearance of SLI by the perfusate without the liver was 12-43% of liver clearance, depending on the peptide examined. These results support the hypothesis that aminopeptidase and endopeptidase activities are involved in SRIF clearance by the intact liver. The activities appear to function independently. The intrachain disulfide bond of SRIF may confer relative stability during its hepatic metabolism.
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PMID:Somatostatin metabolism: differences in clearance of N-terminal and central portions of molecule during perfusion of rat liver. 614 53

A sensitive and specific RIA system has been developed for measuring somatostatin (SRIF) in plasma. On chromatographic analysis of the plasma of portal blood of rats, two peaks of SRIF-like immunoreactivity were found, one (large form) near the position of albumin and the other (small form) in the same position as synthetic SRIF. The nature of the large form is unknown, but the small form was immunologically and physicochemically indistinguishable from synthetic cyclized SRIF. After iv injection of substance P (10 micrograms/100 g BW) into rats, there was a significant increase in the portal plasma level of SRIF from the basal values of 277 +/- 75 to 1130 +/- 111 pg/ml at 15 min. On the other hand, the pancreatic SRIF concentration decreased from 0.27 +/- 0.01 to 0.16 +/- 0.04 ng/mg wet wt at 15 min and was maintained at a low level up to 30 min after the injection. Injection of substance P did not affect the SRIF concentration in the stomach. Similar results were obtained after iv administration of neurotensin (3 micrograms/100 g BW). These findings suggest that increases in the portal plasma levels of SRIF in rats treated with substance P or neurotensin may reflect, at least in part, the release of SRIF from the pancreas. The physiological significance of SRIF secretion remains to be clarified, but this study suggests that SRIF can be released from the digestive organs, including the pancreas, into the portal vein and may act on the tissues in the peripheral area.
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PMID:Effects of substance P and neurotensin on somatostatin levels in rat portal plasma. 615 2

Somatostatin, in concentrations up to 100 ng/ml, had no effect on mast cell secretion induced either by compound 48/80 or by the ionophore A23187. In higher concentration somatostatin induced mast cell secretion. Light and electron microscopic observations showed that the secretory response was identical with that induced by 48/80 and involved extrusion of secretory granules by exocytosis. As with 48/80, this response to somatostatin was inhibited by treating the mast cells with EDTA or EGTA or by exposing them briefly to A23187 in calcium-free media, all of which procedures seemingly deplete cellular calcium stores. Reintroduction of calcium (but not magnesium), restored secretory responsiveness. Somatostatin-induced secretion further resembled that induced by 48/80 or A23187 in its intensity, rapid time course, and dependence on albumin. Pretreatment of mast cells with dibutyryl cyclic AMP or 8-bromo cyclic AMP substantially reduced the secretory responses to both somatostatin and 48/80 but had little effect on the response to A23187. Somatostatin, like 48/80, lowered intracellular cyclic AMP levels in a time and dose-dependent fashion. Finally, as earlier found for 48/80, somatostatin attached to Sepharose columns retarded the passage of mast cells and elicited histamine release indicating an action at the cell surface. The stimulant action of somatostatin is thus very similar to that of the classic mast-cell secretagogue compound 48/80.
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PMID:Somatostatin-induced histamine secretion in mast cells. Characterization of the effect. 616 54

The present study deals with the origin of somatostatin in cerebrospinal fluid. Two groups of experiments were performed: (1) Diagnostic lumbar puncture was performed in 37 patients admitted for various neurological diseases. Immunological determination of albumin and gamma-globulin, and radioimmunological analysis of somatostatin in successive cerebrospinal fluid taps demonstrated that while the protein concentration was approximately 20% lower in the 11th ml compared to the 1st ml drawn, the somatostatin concentration was constant. (2) Intravenous arginine infusion (30 G/30 min) induced identical patterns of plasma growth hormone in 8 patients with multiple sclerosis in relapse, in 6 patients with multiple sclerosis in the stable phase, and in 7 patients in whom no neurological disease was eventually diagnosed. Cerebrospinal fluid somatostatin was significantly lower in the patients with multiple sclerosis in relapse than in the two other groups, while cerebrospinal fluid growth hormone concentration was identical. There was no correlation between basal or arginine provoked plasma growth hormone and the cerebrospinal fluid content of somatostatin. The results indicate that cerebrospinal fluid somatostatin is released dispersely from the central nervous system including the spinal cord - and that it offers no indication of the activity or tone of hypothalamic growth hormone release inhibiting control of the pituitary gland.
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PMID:The origin of cerebrospinal fluid somatostatin: hypothalamic or disperse central nervous system secretion? 616 19

Postprandial elevation of 5-phosphoribosyl 1-diphosphate (PPRibP) concentration in the mouse liver (Lalanne, M. and Henderson, J.F. (1975) Can. J. Biochem. 53,394-399) was further studied regarding the effects of protein intake and the underlying mechanisms. The extent and duration of the increase depended on the quantity and quality of proteins ingested. The order of effectiveness of various diets was as follows: 60% casein greater than 20% egg albumin greater than 20% casein greater than 20% gelatin = 20% gluten greater than 20% zein greater than 0% casein. Hepatic purine and pyrimidine biosyntheses de novo, as measured by labelled tracer incorporation, increased with increasing protein intake. Nicotinic acid incorporation into NAD increased equally, whether casein-containing or casein-free diets were given. Therefore, the increase of PPRibP level may be brought about by increase in its synthesis. Administration of glucagon or epinephrine similarly elevated the hepatic level of PPRibP. Somatostatin, known to inhibit secretion of pancreatic hormones, suppressed the casein-diet-dependent PPRibP level increase. Colchicine markedly inhibited the casein-diet- and glucagon-dependent responses, but not the epinephrine effect. It is likely that glucagon is a major factor in mediation of the protein-diet-dependent PPRibP level increase and that the cytoskeleton is involved in the glucagon-mediated response.
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PMID:Protein-diet-induced elevation of 5-phosphoribosyl 1-diphosphate concentrations in mouse liver associated with increased syntheses of various nucleotides and the possible involvement of glucagon. 620 43

We have used fractionation on density gradients of Percoll to separate the cell types in the rat anterior pituitary gland and to produce a purified preparation of somatotrophs. The method differs from those described previously which used, for example, albumin or Ficoll gradients, in being more rapid and avoiding low temperatures, and therefore gives cells with improved viability. Anterior pituitary glands from male rats were dispersed with trypsin to produce 1.5 x 10 (6) -2.0 x 10 (6) cells/gland. These were fractionated on hyperbolic density gradients of Percoll. Two bands of cells containing somatotrophs were detected, one of which (band A; density 1.075-1.082 g/cm3) contained approximately 90% somatotrophs, whereas the other (band B; density 1.055-1.068 g/cm3) contained about 70% somatotrophs mixed with other cells, especially lactotrophs. Cells in band A appeared more responsive to secretagogues than those in band B; growth hormone secretion was stimulated markedly by cyclic AMP derivatives and prostaglandin E2, and inhibited by somatostatin. Such purified somatotrophs are well suited to biochemical studies on the mechanism of the control of growth hormone secretion.
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PMID:A procedure for the purification of somatotrophs isolated from rat anterior pituitary glands using Percoll density gradients. 628 34

Dissolving basic peptides such as insulin, secretin, and somatostatin in albumin-containing solutions increases the biologic potency. As CCK-33 also constitutes a basic peptide, it should have similar qualities. In four conscious dogs with chronic gastric and pancreatic Thomas fistulas, we studied the effect of CCK-33 solutions with and without addition of albumin on pancreatic secretin, plasma PP concentration, CCK-like immunoreactivity in plasma and infusion lines. The response of pancreatic protein output (mg/15 min) to increasing doses of 99% pure CCK-33 (0.5; 1; 2; 4 IDU/kg/h) was significantly higher (p less than 0.05) when CCK was dissolved in 0.154 M NaCl with albumin than in NaCl alone. These results were confirmed by measuring plasma CCK-immunoreactivity by CCK-RIA and CCK-immunoreactivity in samples from tips of infusion lines by gastrin-RIA. CCK evoked PP release at increasing doses of CCK-33, which was significantly (p less than 0.05) higher when CCK was dissolved in an albumin-containing solution. There was a significant (p less than 0.02) correlation between plasma PP concentration and pancreatic protein output. Our study shows addition of albumin to solutions of CCK-33 to cause an increase of CCK-33 activity, probably by preventing adsorption of the peptide to glass and plastic surfaces. This is valid for its effect on pancreatic protein secretion as well as PP release.
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PMID:[Addition of albumin to solutions of cholecystokinin (CCK)--effect on pancreatic secretion, plasma CCK level and release of pancreatic polypeptide (PP)]. 686 20

The importance of alpha-keto acid binding to plasma proteins was investigated both in vitro and in vivo using alpha-ketoisocaproate (KIC), the alpha-keto acid of leucine. Gel chromatography indicated that 65% of the radioactivity comigrated with serum albumin. An ultrafiltration assay was developed to estimate the percentage of free and bound KIC. These percentages, along with total plasma KIC concentrations, were used to calculate the circulating concentrations of free and bound KIC. KIC or free fatty acids (FFA) displaced [14C]KIC bound to bovine albumin or whole plasma. KIC was totally displaced from plasma proteins by 10 mM oleate, stearate, and myristate; whereas the alpha-keto acids of isoleucine and value were 50 and 85%, respectively, as effective as KIC. To determine whether increased plasma FFA concentrations alter the binding of KIC to plasma proteins in vivo, five postabsorptive humans were infused with triglyceride and heparin during the simultaneous administration of somatostatin, glucagon, and insulin. During the FFA elevation, plasma leucine decreased by 9% (P less than 0.02). Total plasma KIC remained constant, whereas free KIC increased (P less than 0.02) and bound KIC decreased (P less than 0.001). These results indicate that KIC is bound to plasma albumin in vivo and suggests that FFA, by altering circulating free KIC concentrations, may influence protein metabolism in man.
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PMID:Regulation of alpha-ketoisocaproate binding to albumin in vivo by free fatty acids. 703 54

The purpose of this study was to delineate the possible endocrine effects of exercise-induced GH secretion. Twelve healthy adult males were studied during short (20 min) and subsequent prolonged (2 h) physical exercise and recovery period (2 h), both after injection of a long acting somatostatin analog [Sandostatin (ST); 0.1 or 0.05 mg, sc] and after a control saline injection. Additional subjects were studied during rest with similar injections of ST (0.1 mg) and saline (n = 7) or using a lower ST dose (0.01 mg; n = 6). Several venous blood samples were taken during the trials and analyzed for selected hormones, monitoring pituitary, testicular, and adrenal functions. ST injection blocked the serum GH response to short term maximal bicycle ergometer exercise, but not to the following prolonged bicycle exercise. No relationship of the exercise-associated GH increase to the concomitant endocrine responses of the adrenals and testes was observed. Unexpectedly, the higher ST doses (0.1 and 0.05 mg) increased the mean levels of serum testosterone by 18-25% in both exercise (P = 0.0017) and rest trials (P < 0.0001), respectively. ST did not affect the levels of LH, FSH, or cortisol. ST slightly increased serum sex hormone-binding globulin (3%; P = 0.021) and albumin (4%; P = 0.017) concentrations, but not that of free testosterone. Because the testosterone response to somatostatin was fast and without a simultaneous increase in LH, it was consistent with a direct testicular response. The explanation for this novel ST effect remains obscure, but it may be due to modulation of some paracrine mechanisms inhibiting testicular steroidogenesis.
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PMID:Effects of a long acting somatostatin analog on pituitary, adrenal, and testicular function during rest and acute exercise: unexpected stimulation of testosterone secretion. 759 42

This study was undertaken to examine the effects of increasing doses of rat somatocrinin (GRF) with or without a somatostatin antiserum (SS-ab) on serum hormone and metabolic concentrations, as well as serum and duodenal cholecystokinin (CCK) and antral gastrin concentrations. 24-day-old male Sprague-Dawley rats were injected twice daily s.c. (10:00 and 16:30) for 14 consecutive days with either saline or rat GRF (1-43) NH2 (4 and 20 micrograms/kg) in gelatin. Three other groups of animals received the same treatment in association with the SS-ab given i.p. every other day making up the 6 groups of 12 animals in a 2 x 3 factorial design experiment. GRF treatment increased circulating growth hormone (GH) concentrations in a dose-dependent manner, alone or in combination with the SS-ab; the SS-ab treatment alone or combined with GRF also increased GH concentrations. Total hypophyseal GH content was increased (P < 0.05) by the GRF treatment alone. Serum levels of IGF-1, acetoacetate, alpha 2 globulin and antral gastrin were all increased by the GRF treatment with plateaus observed for antral gastrin and serum IGF-1 levels at the intermediary dose of GRF. Serum concentrations of T4 were reduced at the 4 micrograms/kg dose of GRF. Serum concentrations of CCK were increased by the SS-ab treatment alone, an effect reversed by increasing doses of GRF. Rat GRF produced a dose-dependent increase and decrease of alpha 2 globulin and albumin, respectively. These data indicate that GRF, probably via its effect on GH release, influences gastrointestinal hormone levels which are implicated in gastrointestinal organ growth and digestive processes.
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PMID:Effects of GRF with or without a SRIF antiserum on GH, IGF-1, thyroxin, cholecystokinin, gastrin and metabolite concentrations in growing rats. 795 Sep 3


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