Difference in effects of sodium fluoride and cholecystokinin on diacylglycerol accumulation and calcium increase in guinea pig gastric chief cells |
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Authors: | O Nakano C Sakamoto H Nishisaki Y Konda K Matsuda K Wada M Nagao T Matozaki |
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Institution: | Second Department of Internal Medicine, Kobe University School of Medicine, Japan. |
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Abstract: | In isolated guinea pig gastric chief cells, sodium fluoride (NaF) stimulated a monophasic increase in diacylglycerol accumulation, while cholecystokinin (CCK) strongly stimulated its biphasic accumulation. NaF evoked an increase in initial Ca2+ influx rate with a slow increase in intracellular free Ca2+ concentration ( Ca2+]i), while CCK stimulated a rapid increase in Ca2+]i followed by a late sustained phase of the Ca2+]i increase. Lanthanum chloride (La3+) effectively blocked NaF-stimulated increase in Ca2+]i, but it blocked only CCK-stimulated late sustained phase of Ca2+]i increase. The effect of NaF on pepsinogen secretion was enhanced in the presence of 100 microM AlCl3. Furthermore, pertussis toxin did not affect NaF-evoked diacylglycerol accumulation at all. These results suggest that NaF may activate a pertussis-toxin insensitive guanine nucleotide regulatory protein (G protein) coupled to a signal transducing mechanism which seems to be distinct from that activated by CCK, thereby inducing increases in diacylglycerol accumulation, Ca2+ influx and pepsinogen secretion in guinea pig gastric chief cells. |
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