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Vasoactivity of somatostatin and its clinical use
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PARACRINE CONTROL OF GASTRIC SECRETION IN PROTOCHORDATES M C Thorndyke and P J R Bevis, Dept. Zoology, Bedford College, London, U.K. A perfused stomach preparation from the ascidian StyeLfz cl~ua has been developed which allows investigation of gastric enzyme secretion. Protochordates are simple animals and provide an ideal model system for the study of the evolutionary development of peptide-target organ interactions. Styela has a simple gastrointestinal tract which nevertheless shows the beginnings of specialization. Typical gut endocrine cells have been described containing a secretin-like factor, whilst adjacent in the epithelium lie both enzyme protein and acid phosphatase producing cells. Gastric secretion is assayed as protein and acid phosphatase levels in the perfusate. Parallel perfusion of the gastric blood system, with various concentrations of Boots or Sigma secretin produces a characteristic dose response relationship. Control perfusions produce zero or only negligible increases in perfusate levels of protein or acid phosphatase. However, when pure synthetic secretin (Peninsula) was used, no gastric secretion was detectable. When synthetic CCK octapeptide (26-33) was used, a massive release of gastric protein and acid phosphatase ensued. These results suggest that although this protochordate peptide is more secretin-like in in~unocytochemical tests, its biological activity is more CCK-like, and furthermore it controls gastric secretion in a paracrine fashion. This, for the first time, aptly illustrates an interesting and crucial stage in the evolutionary development of the control of gastrointestinal secretion whereby at this level of complexity a secretin/CCK-like peptide is acting at a purely local level. Only later with establishment of the pancreas as a separate source of enzymes did the classic endocrine pathway emerge.
VASOACTIVITY OF SOMATOSTATIN AND ITS CLINICAL USE L. Thulin, H. SamnegSrd,
G. Tyd~n, I. Magnussun and S. Efendic
Department of Surgery, Huddinge Hospital
• -i Cyclic sumatustatin was given intravenously at a dosage of 1 ug.kg-l.mln during I min. In anaesthetized dogs, the flows decreased in the portal vein and in the left gastric, superior mesenteric and pancreatico-duodenal arteries by 20-30 %. Cardiac output, hepatic artery flow and arterial pressure did not change. In patients anaesthetized for surgery, flows decreased in the common hepatic, splenic, ileocolic and left colic arteries by 25-35 %. Fluws in internal carotid artery and coronary bypass grafts did not change. External iliac flow increased by 25 % and arterial pressure by 20 %. Thermodilution, - and electromagnetic techniques were used in the above-mentioned studies. In unanaesthetized patients during angiography, arterial vasoconstriction was found in all intra-abdominal organs. Elevated portal pressure in cirrhotics decreased by 20-30 %. Since sumatostatin thus reduced splanchnic blood flows and portal pressure without affecting central circulation, it appeared indicated to use the peptide against bSeeding due to portal hypertension. Somatustatin at a dosage of 100-250 ug.hr-- during 2-12 hrs was given to nine consecutive patients with enduscupically proved massive hemorrhage from uesophageal varices. Bleeding stopped in immediate temporal relation to infusions on twelve occasions and no rebleeding occurred during treatment.
PARACRINE CONTROL OF GASTRIC SECRETION IN PROTOCHORDATES M C Thorndyke and P J R Bevis, Dept. Zoology, Bedford College, London, U.K. A perfused stomach preparation from the ascidian StyeLfz cl~ua has been developed which allows investigation of gastric enzyme secretion. Protochordates are simple animals and provide an ideal model system for the study of the evolutionary development of peptide-target organ interactions. Styela has a simple gastrointestinal tract which nevertheless shows the beginnings of specialization. Typical gut endocrine cells have been described containing a secretin-like factor, whilst adjacent in the epithelium lie both enzyme protein and acid phosphatase producing cells. Gastric secretion is assayed as protein and acid phosphatase levels in the perfusate. Parallel perfusion of the gastric blood system, with various concentrations of Boots or Sigma secretin produces a characteristic dose response relationship. Control perfusions produce zero or only negligible increases in perfusate levels of protein or acid phosphatase. However, when pure synthetic secretin (Peninsula) was used, no gastric secretion was detectable. When synthetic CCK octapeptide (26-33) was used, a massive release of gastric protein and acid phosphatase ensued. These results suggest that although this protochordate peptide is more secretin-like in in~unocytochemical tests, its biological activity is more CCK-like, and furthermore it controls gastric secretion in a paracrine fashion. This, for the first time, aptly illustrates an interesting and crucial stage in the evolutionary development of the control of gastrointestinal secretion whereby at this level of complexity a secretin/CCK-like peptide is acting at a purely local level. Only later with establishment of the pancreas as a separate source of enzymes did the classic endocrine pathway emerge.
VASOACTIVITY OF SOMATOSTATIN AND ITS CLINICAL USE L. Thulin, H. SamnegSrd,
G. Tyd~n, I. Magnussun and S. Efendic
Department of Surgery, Huddinge Hospital
• -i Cyclic sumatustatin was given intravenously at a dosage of 1 ug.kg-l.mln during I min. In anaesthetized dogs, the flows decreased in the portal vein and in the left gastric, superior mesenteric and pancreatico-duodenal arteries by 20-30 %. Cardiac output, hepatic artery flow and arterial pressure did not change. In patients anaesthetized for surgery, flows decreased in the common hepatic, splenic, ileocolic and left colic arteries by 25-35 %. Fluws in internal carotid artery and coronary bypass grafts did not change. External iliac flow increased by 25 % and arterial pressure by 20 %. Thermodilution, - and electromagnetic techniques were used in the above-mentioned studies. In unanaesthetized patients during angiography, arterial vasoconstriction was found in all intra-abdominal organs. Elevated portal pressure in cirrhotics decreased by 20-30 %. Since sumatostatin thus reduced splanchnic blood flows and portal pressure without affecting central circulation, it appeared indicated to use the peptide against bSeeding due to portal hypertension. Somatustatin at a dosage of 100-250 ug.hr-- during 2-12 hrs was given to nine consecutive patients with enduscupically proved massive hemorrhage from uesophageal varices. Bleeding stopped in immediate temporal relation to infusions on twelve occasions and no rebleeding occurred during treatment.