Activation of CCK-B receptors elevates cytosolic Ca2+ levels in a pituitary cell line.
Cytosolic Ca2+ levels ([Ca2+]i) in GH3 cells, a rat anterior pituitary tumor cell line, were monitored with fura-2 by fluorescence measurements. Cholecystokinin octapeptide (CCK-8) produced a transient elevation of [Ca2+]i. The elevation of [Ca2+]i by CCK-8 was inhibited by L-365,260, but not by devazepide. It was still observed when extracellular Ca2+ was eliminated, indicating that CCK-8 mobilizes Ca2+ from intracellular storage sites after interaction with CCK-B receptors. Cholecystokinin octapeptide increased the turnover of phosphatidylinositol, but it did not affect cyclic AMP levels. A possible involvement of phosphatidylinositol breakdown and calcium mobilization in the transduction system of CCK-B receptors in GH3 cells is suggested.
Kuwahara
T
T
Department of Pharmaceutical Screening, Nippon Roche Research Center, Kamakura, Japan.
Nagase
H
H
Takamiya
M
M
Yoshizaki
H
H
Kudoh
T
T
Nakano
A
A
Arisawa
M
M
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism*; D016257:Fura-2; D066298:In Vitro Techniques; D010716:Phosphatidylinositols / Q000378:metabolism; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D043887:Receptor, Cholecystokinin B; D011949:Receptors, Cholecystokinin / Q000187:drug effects*; D012844:Sincalide / Q000494:pharmacology
D010716:Phosphatidylinositols; D043887:Receptor, Cholecystokinin B; D011949:Receptors, Cholecystokinin; D000242:Cyclic AMP; D012844:Sincalide; D002118:Calcium; D016257:Fura-2