8/11/2019 Digestive-Absorptive Function of the Intestinal Brush
Border in Uremia
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1642 T he A m er ica n Journa l o fC lin ica l N u trition 31:
SE PTEM BER 1978 , p p . 16 42 -16 46 . P rin ted in U .S .A .
D iges tive abso rp tive fun c tio n o f th e
in te s tin a l b rush bo rde r in u rem ia
V . W izem ann D . L u dw ig R . K uh i a nd I. B u rgm ann
ABSTRACT Am ino acid ab sorp tio n w as stu d ied in chron ic
urem ic ra ts. In tes tina l tran spo rt o f
L -leuc ine appears to be in h ib ited w ith m ild urem ic in
tox icat ion , w hereas seve re urem ia en hance s
absorp tion . B ru sh b ord er activ ity of in tes tin al m
altase and d isa cch aridases is h igh er in ra ts w ith
chron ic renal in suf fic iency . Th e sam e ho lds fo r -y-g lu
tam y l-tran spep tid ase ac tiv i ty .
Am . J . C lin .
Nut . 31: 164 2-1 646 , 19 78 .
A ltho ugh m orpho log ica l d iso rd ers o f th e
gastro - in te stina l tract in u rem ia a re w ell do c -
um en ted (1 -3 ), co n if ictin g da ta h av e been
repo rted co nce rn in g in tes tin a l su ga r an d
am ino ac id transp ort a s w e ll a s m u co sa l d i-
sacch aridase an d d ipep tid ase activ ities in
rena l fa ilu re (2 , 4 -8 ). T he con trad ic ting re -
su lts m ay b e exp la in ed by d iffe ren t g rad es o f
u remia
and by the exp e rim en ta l d esig n . S p e -
cif ic d igestiv e en zym e ac tiv ity had no t been
m easu red in the m uco sal b rush b orde r w here
m ost o f th e enzym es are loca ted , b u t in to ta l
m ucosal hom og en ate .
F o llow ing th e concep t o f C rain e (9 ) the
in te stina l b rush b ord e r m em b rane is a d iges-
live -abso rp tive su rface, w he re th e enzym es
located at the lum ina l m em brane of the m u-
co sa a re invo lved in the transep ith eia l trans-
po rt o f su ga r and am ino acid s.
U s ing a b ru sh borde r p repa ra tion , d isac -
ch aridase and d ip ep tida se ac tiv ity o f in tes -
tina l m ucosa w as d ete rm ined in n orm a l and
in 9 0 nephrectom ized ra ts . R e fe rr ing to the
hy po th esis o f O rlow sk i and M eiste r (1 0 ) tha t
m em b rane bound -y -g lu tam yl transpep tida se
p lays a ro le in am ino ac id transport the en -
zym e w as m easu red too . In o rd er to es tim a te
the ov era ll e ffec t o f u rem ia on in te stina l
am in o ac id abso rp tion , a p repa ra tion of iso -
la ted pe rfused ilea l segm en ts w as used .
Me th o d s
O ne hundred s ix te en m ale ra ts o f a S iv str a in body
w eig h t 3 38 22 g)
w ere u sed as exp e rim en ta l an im a ls
U rem ia w as in du ced by 90 nep hre ctom y . A bou t 6 to
8
w eek& af ter the op era tio n , serum ure a leve l w as 222
27
m g/ 1 00 m l (co n tro l g roup 48 8 m g/l00 m l) . The
an im a ls had fre e ac ces s to A ltrom in-d iet and w ater
.
Th e brush border m em b ran e w as iso late d accord ing
to th e m e tho d of H opfe r et a l . (1
l).2 In th e m em b rane
f ract ion , ac tiv i ties of th e d isa cch aridases (lacta se
, ce ll
lo b iase, sa cchara se , m a ltase) w e re d ete rm ined by
th e
m eth od of D ahlqv ist (1 2), the d ip ep t ida ses L-leucy
l-L-
le uc ine, L -m eth ion yl-L -m eth io n in e, L -m eth ion yl-L
-le u-
c ine , L - leucy l-g ly cin e, g ly cin e-L -leu cin e, L -p ro
line-L -leu-
cin e) ac cord in g to C a spa ry et al . (14 ).
Th e tran spo rt stu d ie s h ad been p erfo rm ed w ith
iso-
la ted pe rfu sed ilea l s egm en ts of norm a l an d u rem ic
rats .
4C -L -le ucine w a s u sed .
Resu l ts
In the b rush bo rd er p repa ratio n , d isac -
cha ridase s w ere en riched 13 - to 32 -fo ld co rn -
pa red to the ac tiv ity in the to tal hom og en ate .
T he en richm en t o f d ipep tid ases in the m em -
bran e frac tion w as com para tive ly sm alle r
(F ig . 1 ).
T he m easu rem en ts o f d isaccha ridase s
sh ow ed tha t ch ro n ic rena l fa ilu re on ly h ad an
e ffec t o n brush borde r m a lta se activ ity , w h ich
w as enh an ced
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