Efecto de fracciones pépticas derivadas de la caseína en la absorción de D-xilosa y motilidad intestinal en el perro: estudio preliminar / Effect of casein derived peptides on D-xylose absorption and small intestinal motility

Background: The presence of food in the intestinal lumen increases absorption from an isolated intestinal loop, the mechanisms involved are unknown. Casein, and its respective hydrolysate, increased D-xylose absorption in both normal volunteers and experimental animals; this effect was associated with prolonged small intestinal transit time and a decrease of motor activity. Aims: To separate from casein hydrolysate, groups of peptides and to investigate their effects on both D-xylose absorption and small intestinal motility. Material and methods: Studies were performed on five dogs with a surgically implanted duodenal cannula. Three groups of peptides were separated by means of a Silica Gel 60 column and were continously infused through the duodenal cannula. After 15 min, 5 g of D-xylose were injected in the duodenum, plasma levels were measured, and the area under the curve was estimated. Motility was recorded by means of infused catheters and external transducers. Results: Plasma levels of D-xylose were significantly increased during the infusion of one group of peptides compared to the others. In addition, the area under the curve: 3366 ñ 885 mg x min-1 observed with this group was significantly greater than the other two groups: 1432 ñ 183 mg x min-1 and 1137 ñ 280 mg x min-1 respectively. No statistically significant differences in motor activity were observed between the different groups of peptides. Conclusions: A group of peptides derived from casein was characterized by increasing D-xylose absorption. The presence of beta casomorphines might be the possible mechanism involved

Neuropeptide control of the cardiovascular system in fish and reptiles

Accumulating evidence shows the involvement of neuropeptides in cardiovascular control in mammals as well as non-mammalian species. Our own immunohistochemical studies indicate a sparse innervation only in cyclostomes, holostean fish and lungfish, a more extensive variation and distribution in elasmobranchs and teleosts, and a rich and varied innervation of the cardiovascular system in crocodiles and lizards. Vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY), gastrin releasing peptide (GRP) and tachykinins are present in most vertebrate groups. VIP is vasodilatory in the Atlantic cod (Gadus morhua) as in most mammalian species, but increases gut vascular resistance in the spiny dogfish (Squalus acanthias). NPY potentiates the effect of noradrenaline on skate (Raja rhina) coronary vessels, suggesting an interaction between adrenergic mechanisms and NPY early in evolution, but studies in the spiny dogfish and the crocodile also demonstrate different mechanisms for the action of NPY and adrenaline in some species. Bombesin/GRP increases flow to the gut in the spiny dogfish by an increase in somatic vascular resistance, while visceral resistance remains unchanged. In the caiman (Caiman crocodylus crocodylus) bombesin causes a shunting of blood from the lung to the gut. Substance P and other tachykinins in general increase flow to the gut, and on some occasions also increase somatic blood flow. Flow in the anastomosis of the crocodile (Crocodylus porosus) gut is increased by substance P. The results presented here are a review of several published and unpublished studies.

Polipeptídeo vasoativo intestinal (VIP) no útero de mamíferos: distribuiçäo, origem e efeitos / Vasoactive intestinal polypeptide (VIP) in the mamalian uterus: distribution, origin and effects

Procedeu-se a uma revisäo bibliográfica sobre a distribuiçäo, origem e possíveis papéis fisiológicos do neurotransmissor polipeptídeo vasoactivo intestinal (VIP), no útero. O VIP está presente no útero de mamíferos em geral, localizando-se em fibras nervosas, cujo número é maior na cervice uterina em comparaçäo com o restante do órgäo. As fibras nervosas vipérgicas orientam-se ao longo de células musculares lisas e ao redor de glândulas e vasos sanguíneos, e originam-se dos gânglios nervosos paracervicais, situados na junçäo cérvice uterina-vagina. Os efeitos do VIP no útero, encontrados até o momento, säo os seguintes: 1) relaxamento da musculatura lisa uterina; 2) vasodilataçäo; 3) possível participaçäo em processos secretores.