Update in Small Bowel Physiology: Part 1

Abstract

The recent advances in cl inically imporrnnt d iseases of the small mtestine have been reviewed; however, the basis for many of t hese clinical advances rests wi th important observations on alterations in the ph ysio logy of the small intestine, as well as mechanistic observa tions of altera tions in small intestinal function in mode ls of human disease. In th is review a summa ry of the past year's literature is p resented whic h will draw attention t0 the considerable areas of progres in small bowel physio logy wh ich will soon be rnmsla ted into an improved understanding of the pathophys iology of a varie ty of intestinal disorders. Can J Gastrocnterol 1990;4(6)243-254 Derniers developpements clans la physiologie du grele: Premiere partie RESUME: Le present article proccde a la rev ue des progres recemment realises dans les maladies du grele q ui sont d'interet clinique; neanmoins, nombre de ces progres cliniques sonr fondes sur des observations importances des alte rations de la physiologic du grele, ainsi que sur des observations mecaniques de altern tions fonctionnclles du grele clans des modeles e xperimenra ux de malad ies humaincs. Les auteurs proposen t un sommairc Je la lirrerature de l'annee preceden ce, soulignanr ainsi l'ampleur consi<le rable des progres realises J ans la physio logie de l'intestin grele, lcsquels se tradui ront bien tot par une meilleure comprehe nsion <le la phys iopathologie d'une variete d'affections inrestinales.T l le RECENT ;\[)VANCE~ IN <'LINlca ll y import ant diseases of rhe ~mall intestine h,1ve hecn reviewed ( l ); however, thl"' h,1sis for many n( t hese clinical advances rcbls wit h important ohserva t ions on alterati\)ns in the physiology of the small 1111 est inc, as we ll as mechanistic nhservatiuns of altern11ons in small intesti nal func u on in modds(if h uman disease. In rh b review, a summmy ()f the past year's literature is presented wh ich drnws mte n tinn to the Dit•isron of ( ,c1~1me11rerolo.rn considerabl e progress in small howcl physirilogy which will '>0011 be tra nslated into an 1mrroved understanding ot the pmhor,hy1,io lngy nt a variety o( imcst mal cl isnrdcrs.CARBO HYDRATES The muleculm organization o( the 111 tcst i nal h rush horde r me m hra n e (BBM) ha~ hccn reviewed (2). Un 14ue isuactms have heen idcmificd in the BBM of ra1 intestinal epithelial cells (3). The plasmn membranes of most mmnmal1an cells have an exrernall y exj)()Scd layer of carbohydrntcs. These ca rhohydrate mn1e1 1es arc associated with glycnprote1m ,1nd glycnlirids, playing an im ponanr rule in growth regulation, cell ad hesion, recognitton anJ antigcnici t y. There are diffe rences in the glycorrotcm and glycolip1d compositi ons of BBM and hasola t ernl mcmhranes (BLM) of rat small inrestine ( 4). Perhaps the hcst c haracterized ot t he stalked me mbrane proteins is the sucrasc-iM1111 altase comr lex wh ic h r,rojccts from the BBM surface into the mternrnd lumen. Phnspho l ipasc B also has the characteristtcs of a stalked BBM prnte m ( 5). G lucose: lntesrinal...