Cholecystokinin increases intracellular Ca 2+ concentration in the Human JURKAT T Lymphocyte Cell line

Abstract

We have recently demonstrated the presence of specific high-affinity cholecystokinin binding sites of the central type on the Human JURKAT T Lymphocyte Cell line. In this paper, changes in intracellular Ca 2+ concentration ([Ca 2+] i) in response to CCK (cholecystokinin) peptides were measured in the Human JURKAT T Lymphocyte Cell line by fura-2 fluorometry. CCK-8 (the C-terminal octapeptide of CCK), the potent CCK analog Boc-[Nle 28,31]CCK-7, stimulated ([Ca 2+] i) mobilization in a dose-dependent manner in cells preloaded with fura-2 AM with an EC 50 of 2.4 ± 1 nM and 8 ± 2 nM, respectively. The selective CCK B receptor agonists, namely BocTrpNleAspPheNH 2 and the cyclic analog JMV320, AcTyrLysGlyTrpLysAspPheNH 2, were also potent in stimulating mobilization of [Ca 2+] i with an EC 50 of 32 ± 10 nM and ▪25 ± 10 nM, respectively. Compound JMV180, BocTyr(SO 3H)NleAsp-2-phenylethyl ester, did not stimulate [Ca 2+] i but inhibited the mobilization of [Ca 2+] i elicited by 10 nM CCK-8 in a dose-dependent manner with an IC 50 of 10 ± 2 nM. The selective non-peptide CCK B receptor antagonist L-365,260 was more potent than the selective CCK A receptor antagonist MK-329 in inhibiting the [Ca 2+] i elicited by 10 nM CCK-8 with IC 50 values of 20 ± 8 nM and 400 ± 100 nM, respectively. These data indicated that CCK-8 and potent CCK analogs induced [Ca 2+] i mobilization in the Human JURKAT T cell line through the CCK B/gastrin receptor type.