The effects of natural secretin (90%) and synthetic secretin as well as impure (10%) and pure (99%) cholecystokinin-pancreozymin (CCK) on net absorption of water, electrolytes, and glucose in human jejunum were studied in 31 normal subjects. An intestinal perfusion technique with a triple-lumen tube was used. Net absorption of water and solute was significantly inhibited by both hormones only with larger doses, pure CCK being less active than impure CCK. A dose-dependent response of water and electrolyte absorption to graded doses of pure CCK was observed, without concomitant inhibition of glucose absorption with lower doses. The findings suggest that secretin and CCK may not be of physiologic importance regarding intestinal absorption in man. The definite changes in intestinal motility and transit rate caused by these hormones seem more likely to result in a reduction of intestinal absorption and an increase in the secretion of water and electrolytes along the proximal small bowel.

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and Conclusions. In 35 metabolically normal subjects the effect of i.v.secretin and eholecystokinin-panereozymin (CCK/PZ) on the endocrine and exoerine pancreatic function was investigated, before and after atropine. In addition, the effect of oral, intravenous and intraduodenal administration of glucose and amino acids on blood sugar and free fatty acids before and after the injection of atropine was studied.The secretin stimulated endocrine and exoerine pancreas was not affected by atropine. However, atropine inhibited the ecbolic and endocrine pancreatic function after stimulation with CCK/PZ. Therefore, the effect of i.v. CCK/PZ seems to be mediated by the cholinergic system, or even a "neuro-hormonal" system which acts synergically or additively.No influence of atropine on the insulin secretion induced by i.v. glucose or amino acids was observed. On the other hand, atropine inhibited the beta-cytotropic effect of glucose and amino acids after oral or intraduodenal administration.These findings indicate that the release of these intestinal hormones is dependent on the cholinergic or parasympathetic system. Zusammen]assung und SchIufl/olgerung. Bei 35 steffweehselgesunden freiwilligenProbanden wurde vor sowie nach Atropingabe die Wirkung der intestinalen Hormone Sekretin und Choleoystekinin-Pankreozymin (CCK-PZ) auf die endokrine und exokrine Pankreasfunktion untersueht. Aul~erdem wurde die Wirkung yon intra-ven6s und oral bzw. intraduodenal verabreichter Glucose und Aminos~iuren auf die * Mit Unterstiitzung dureh die Deutsche Forschungsgemeinschaft. Wesentliche Teile der Arbeit wurden am KongreB der Deutschen und Schweizerisehen Gesellsehaft fiir Verdauungs-und Stoffwechselkrankheiten (Stuttgart, 7.--9. 10. 1971) vorgetragen.Abki~rzungen: Cholecystokinin-Pankreozymin (CCK-PZ), immunologisch meBbares Insulin (IMI), Blutzueker (BZ), freie Fetts~uren (FFS).

Abstract. The effect of propranolol on the induction of endocrine and exocrine pancreatic function by secretin (SC) and cholecystokinin‐pancreozymin (CCK/PZ) was investigated in 35 metabolically normal subjects. Insulin secretion could be inhibited by propranolol after administration of glucose or SC. On the other hand it was not possible to inhibit the CCK/ P2 induced insulin secretion by propranolol. Exocrine pancreatic function was not influenced by the administration of propranolol. Our results suggest that the action of SC on the islet system, like that of glucose, is linked to the β‐adrenergic system.