Cw. Tang et al., CHOLECYSTOKININ RECEPTORS IN HUMAN PANCREAS AND GALLBLADDER MUSCLE - A COMPARATIVE-STUDY, Gastroenterology, 111(6), 1996, pp. 1621-1626
Background & Aims: Cholecystokinin (CCK) receptors mediate pancreatic
secretion and gallbladder contraction. Hitherto, little information on
characteristics of CCK receptors in the human pancreas was available.
This study identifies CCK receptors in the human pancreas and compare
s their characteristics with the CCK receptors in the human gallbladde
r. Methods: Visualization and quantification of I-125-Bolton-Hunter su
lfated CCK octapeptide (I-125-BH-CCK-8) binding to tissue sections of
the human pancreas and gallbladder were performed by storage phosphor
autoradiography. Results: Specific bindings for CCK were visualized in
pancreatic tissue and the smooth muscle layer of the gallbladder. Bin
ding of I-125-BH-CCK-8 to the pancreas was inhibited by agonists with
the affinities (dissociation constant) of CCK (0.11 nmol/L) approximat
e to gastrin (0.15 nmol/L) and by antagonists with the affinities of C
CK-B receptor antagonist (L365,260, 0.18 nmol/L) > CCK-A receptor anta
gonist (lorglumide, 8.1 nmol/L). In contrast to the pancreas, binding
of I-125-BH-CCK-8 to the gallbladder muscle was inhibited with high af
finity by CCK-8 and lorglumide but was replaced to a small degree by g
astrin and L365,260. Conclusions: The subtypes of receptors for CCK in
the human pancreas and gallbladder are different. The human pancreas
predominantly expresses CCK-B receptors, whereas only CCK-A receptors
were localized in the human gallbladder muscle.