Evidence for the presence of somatostatin 28 in plasma

Shoelson, S.; Polonsky, Kenneth S.; Docherty, H.; Jaspan, J.; Rubenstein, Arthur H.

doi:10.2337/diabetes.31.5.474

Cited by 9 publications

(8 citation statements)

References 13 publications

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“…Circulating forms of both S-28 and SRIF have been identified in the portal vein of rats by Patel et al (2) and we have made similar observations in the portal and peripheral circulation of rats and dogs (6). S-28 has not been previously identified in human plasma and its physiological function remains uncertain.…”

Section: Introductionsupporting

confidence: 64%

Plasma somatostatin 28 increases in response to feeding in man.

Polonsky¹,

Shoelson²,

Docherty³

1983

J. Clin. Invest.

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A B S T R A C T Tissue somatostatin-like immunoreactivity (SLI) consists of a number of molecular species including the cyclic tetradecapeptide or SRIF, an Nterminally extended form of SRIF termed somatostatin-28, as well as larger precursor peptides. The function and nature of circulating SLI is not well understood. In this report, we describe techniques for the definition of the components of plasma SLI in normal human plasma. Plasma SLI measured after gel filtration on Bio-gel P-6 columns was found to consist of from 1-3 peaks. The void volume peak was present in greatest concentration (34.2±8.9 pg/ml) and did not increase in response to a mixed meal. Very low levels of two additional peaks of SLI activity were found. To further characterize these peaks, 10-ml plasma samples were extracted and concentrated on octadecylsilyl silica (C-18) cartridges with subsequent fractionation on Bio-gel P-6 columns. The two peaks that coeluted with synthetic SRIF and S-28 markers, respectively, were present in concentrations of 5.4±1.4 and 4.8±1.9 pg/ml in fasting plasma. In response to a mixed meal, the SLI14 peak doubled (12.9±2.4 pg/ml) while the SLI28 peak increased to 29.9±7.2 pg/ml at 120 min. These results provide evidence that S-28 circulates in human plasma and its increase after feeding is consistent with a possible biological role for this peptide.

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Section: Introductionsupporting

confidence: 64%

Plasma somatostatin 28 increases in response to feeding in man.

Polonsky¹,

Shoelson²,

Docherty³

1983

J. Clin. Invest.

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“…Using gel filtration, Schusdziarra et al (15) and Dunning and Taborsky (42), reported that only S-14 increased after feeding dogs a meal of liver in 1 N HCL. Because canine plasma contains S-28 (29), and in our hands, only S-28 increased in dogs fed Ensure (unpublished results), it is possible that acidified liver extract may have led to gastric retention and release of S-14 from the stomach. In man, both S-28 and S-14 have been reported to rise after intake of a mixed meal with most of the increase attributed to S-28 (23,29,30).…”

Section: Resultsmentioning

confidence: 99%

“…Because canine plasma contains S-28 (29), and in our hands, only S-28 increased in dogs fed Ensure (unpublished results), it is possible that acidified liver extract may have led to gastric retention and release of S-14 from the stomach. In man, both S-28 and S-14 have been reported to rise after intake of a mixed meal with most of the increase attributed to S-28 (23,29,30). In this study, we have confirmed the rise in S-28 but we were unable to detect any significant changes in S-14/S-13.…”

Section: Resultsmentioning

confidence: 99%

“…Their precise measurement has been hindered by the use of nonspecific RIA directed to the central region of S-14, precluding their independent quantification in native plasma. S-28 can be separated from S-14 and S-13 by gel filtration and substances with similar elution profiles have been found in plasma of the rat, dog, man, and pig (27)(28)(29)(30)(31). In-creased plasma levels of peptides coeluting with §-28 and S-14 in response to food intake in man have been reported (32,33).…”

Section: Introductionmentioning

confidence: 99%

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Circulating prosomatostatin-derived peptides. Differential responses to food ingestion.

et al. 1989

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Prosomatostatin (pro-S) and its bioactive posttranslational products, somatostatin-14 (S-14), somatostatin-13 (S-13), and somatostatin-28 (S-28), were measured in human plasma by the use of immunoglobulins to the NH2-terminus of S-28 conjugated with agarose to separate them and, thereafter, by RIA with an antiserum recognizing the COOH-terminus of pro-S, and by specific RIA for the NH2-terminus of S-14 and pro-S. In healthy men, mean basal levels of pro-S were 4 pg equivalent S-14/ml; S-14/S-13 combined were 9 pg equivalent S-14/ ml; and S-28 levels were 16 pg/ml. After a 700-kcal meal, pro-S, S-14, and S-14/S-13 did not change, whereas S-28 levels doubled by 120 min and remained elevated for 240 min. To evaluate the origins of these peptides, their levels were compared in peripheral, portal, gastric, and mesenteric veins of anesthetized patients and in patients with total resection of stomach and pancreas before and after nutrient intake. The stomach and small intestine were sources of both peptides; however, most S-28 originated in the small intestine. These findings suggest that, in contrast to S-14, S-28 is a hormone and may modulate postprandial nutrient absorption and use.

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“…This assumption is not made for gastrointestinal output, since the SLI in the gastrointestinal tract and portal venous plasma contains peptides similar to both somatostatin-14 and somatostatin-28 (15,16). Somatostatin-14 does appear to be the predominant form of SLI found in (15,16) and synthesized by (29) the pancreas, although recent studies (30) suggest that a small percentage of the SLI found in the SPDV plasma has a molecular weight similar to somatostatin-28. Furthermore, the influence of interference factors potentially present in unextracted plasma (20) on the calculated output of pancreatic somatostatin is probably eliminated by using net output (venous-arterial SLI times plasma flow).…”

Section: Discussionmentioning

confidence: 99%

Contribution of the pancreas to circulating somatostatin-like immunoreactivity in the normal dog.

Taborsky¹,

Ensinck²

1984

J. Clin. Invest.

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A~bstract. These studies were performed to assess the contribution of the pancreas to the somatostatinlike immunoreactivity (SLI) circulating in arterial and portal venous plasma. Basal SLI concentrations in arterial, pancreatic venous, and portal venous plasma were 95±9, 277±32, and 130±12 pg/mi, (+±SEM), respectively. Measurement of pancreatic and portal venous blood flow (5±1 vs. 365±46 ml/min) and hematocrit allowed calculation of net, base-line SLI output from the right lobe of the pancreas (521±104 pg/min) and from the gastrointestinal tract (8,088±1,487 pg/min), which suggested that the contribution of the pancreas to circulating SLI was minor when the D cells were not stimulated. To stimulate the secretion of SLI from both pancreatic and nonpancreatic sources, isoproterenol, a beta-adrenergic agonist, was infused intravenously for 1 h into six anesthetized dogs. Arterial SLI increased by 52±9 pg/ml; superior pancreatico-duodenal venous SLI increased by 380±95 pg/ml; portal venous SLI increased by 134±14 pg/ml. Pancreatic venous blood flow remained unchanged at 5±1 ml/min, but portal venous blood flow increased to 522±62 ml/min. SLI Volume 73, January 1984, 216-223 organ blood flow, can give a false impression ofthe organ's contributions of circulating SLI. To verify that the contribution of the pancreas was negligible, six dogs received an acute pancreatectomy and then an intravenous infusion of isoproterenol at the same rate. In these dogs, both the base-line level of SLI in arterial plasma (109±12 pg/ml) and the increment during isoproterenol (56±8 pg/ ml) were similar to those of normal dogs. Likewise, in pancreatectomized dogs both the base-line level of SLI in portal venous plasma (129±16 pg/ml) and the increment during isoproterenol (174±34 pg/ml) were similar to those of normal dogs. We conclude that, in normal dogs, the pancreas makes a negligible contribution to the basal and stimulated level of SLI in arterial and portal venous plasma and therefore that these levels should not be used as an index of secretory activity of the pancreatic D cells.

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Evidence for the presence of somatostatin 28 in plasma

Cited by 9 publications

References 13 publications

Plasma somatostatin 28 increases in response to feeding in man.

Plasma somatostatin 28 increases in response to feeding in man.

Circulating prosomatostatin-derived peptides. Differential responses to food ingestion.

Contribution of the pancreas to circulating somatostatin-like immunoreactivity in the normal dog.

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