Cholecystokinin receptors on gallbladder muscle and pancreatic acinar cells: a comparative study
To compare receptors for cholecystokinin (CCK) in pancreas and gallbladder, we measured binding of 125I-Bolton-Hunter-labeled CCK-8 (125I-BH-CCK-8) to tissue sections from guinea pig gallbladder and pancreas under identical conditions. In both tissues, binding had similar time-, temperature-, and pH dependence, was reversible, saturable and inhibited only by CCK related peptides or CCK receptor antagonists. Autoradiography localized 125I-BH-CCK-8 binding to the smooth muscle layer in the gallbladder. Binding of 125I-BH-CCK-8 to gallbladder sections was inhibited by various agonists with the following potencies (IC50):CCK-8 (0.4 nM) greater than des(SO3)CCK-8 (0.07 microM) greater than gastrin-17-I (1.7 +/- 0.3 microM) and by various receptor antagonists with the following potencies: L364,718 (1.5 nM) greater than CR 1409 (0.19 microM) greater than asperlicin = CBZ-CCK-(27-32)-NH2 (1 microM) greater than Bt2cGMP (120 microM). Similar potencies were found for the agonists and antagonists for pancreas sections. Inhibition of binding of 125I-BH-CCK-8 by 11 different analogues of proglumide gave similar potencies for both pancreas and gallbladder. The potencies of agonists in stimulating and antagonists in inhibiting CCK-stimulated contraction or amylase release correlated closely with their abilities to inhibit 125I-BH-CCK-8 binding to gallbladder or pancreas sections or acini, respectively. The present results demonstrate and characterize a method that can be used to compare the CCK receptors in guinea pig gallbladder and pancreas under identical conditions. Moreover, this study demonstrates that gallbladder and pancreatic CCK receptors have similar affinities for the various agonists and antagonists tested and, therefore, provides no evidence that they represent different subtypes of CCK receptors that can be distinguished pharmacologically.
- Research Organization:
- National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD (USA)
- OSTI ID:
- 6603099
- Journal Information:
- Am. J. Physiol.; (United States), Journal Name: Am. J. Physiol.; (United States) Vol. 255; ISSN AJPHA
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
ANIMALS
AUTORADIOGRAPHY
BETA DECAY RADIOISOTOPES
BILIARY TRACT
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL LOCALIZATION
BODY
COMPARATIVE EVALUATIONS
DAYS LIVING RADIOISOTOPES
DIGESTIVE SYSTEM
ELECTRON CAPTURE RADIOISOTOPES
ENDOCRINE GLANDS
GLANDS
GUINEA PIGS
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPES
KINETICS
KININS
MAMMALS
MEMBRANE PROTEINS
MUSCLES
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PANCREAS
PEPTIDES
POLYPEPTIDES
PROTEINS
RADIOISOTOPES
REACTION KINETICS
RECEPTORS
RODENTS
THERMODYNAMICS
VERTEBRATES