Volume 120, Number 3, Page 447

British Journal of Pharmacology

23 January 1997, Volume 120, Issue 3, Pages 447 – 454

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Article

Pharmacological and biochemical evidence for the simultaneous expression of CCK_B/gastrin and CCK_A receptors in the pig pancreas
C. Philippe^1,4, E.F. Lhoste¹, M. Dufresne², L. Moroder³, T. Corring¹ & D. Fourmy²
¹Laboratoire d’Ecologie et de Physiologie du Système Digestif, INRA, Domaine de Vilvert F-78352 Jouy-en-Josas Cedex, France     ²INSERM Unité 151, Institut L. Bugnard, CHU Rangueil, F-31054 Toulouse, France, and     ³Max Planck Institut für Biochemie, Martinsried, Germany

⁴Author for correspondence

Keywords

Pancreas;   CCK_A receptor;   CCK_B/gastrin receptor;   pig

Abstract

1   In the pig, the secretory response of the pancreas is not inhibited by the antagonist MK329 suggesting that cholecystokinin_A (CCK_A) receptors are not involved.
2   Membranes were isolated from the pancreas of 6 Large White pigs to characterize their CCK receptors.
3   The binding of [¹²⁵I]-BH-[Thr, Nle]CCK-9 was dependent on pH, maximal after a 90 min incubation period, saturable and reversible. Saturation analysis of the binding demonstrated a single class of high affinity sites (K_d=0.22±0.02 nM) and a binding capacity, B_max=110.64±12.50 fmol mg^-1 protein.
4   Competition binding by agonists and antagonists of CCK_A and CCK_B/gastrin receptors demonstrated the presence of two distinct binding components, sites presenting a high affinity for [Thr, Nle]CCK-9, gastrin, PD 135158, L-365,260 and a low affinity for MK329, SR 27897, and sites presenting a high affinity for [Thr, Nle]CCK-9, MK329, SR 27897 and a low affinity for gastrin, PD 135158, L-365,260.
5   These pharmacological data demonstrate the presence of both CCK_A and CCK_B/gastrin receptors in the pig pancreas, the latter being predominant.
6   Two distinct membrane proteins (50 and 85 – 100 kDa, respectively) display pharmacological features of CCK_B/gastrin and CCK_A receptors.
7   In pigs, as in calves and humans, CCK_B/gastrin receptors are predominant in the pancreas.

Received 22 April, 96; Revised 20 October, 96; Accepted 31 October, 96