Effects of caffeine on phosphatidylinositide turnover and calcium mobilization in human neuroblastoma SK-N-SH cells.
The effects of caffeine on receptor-controlled Ca2+ mobilization and turnover of inositol phosphates in human neuroblastoma SK-N-SH cells were studied. Caffeine inhibited both the rise in cytosolic Ca2+ concentration ([Ca2+]i) evoked by muscarinic receptor agonists and the total production of inositol phosphates in a dose-dependent manner, but to different extents. At 10 mM, caffeine inhibited agonist-evoked generation of inositol phosphates almost completely, whereas the agonist-evoked [Ca2+]i rise remained observable after caffeine treatment, in the absence or presence of extracellular Ca2+. Raising the cytosolic cAMP concentration increased the carbachol-induced [Ca2+]i rise, and this effect was abolished in the presence of caffeine. Our data suggested that caffeine may exert two effects on receptor-controlled Ca2+ mobilization: 1) inhibition of inositol phosphate production, 2) augmentation of the size of the releasable Ca2+ pool by elevating cytosolic cAMP concentration.
Liu
Pei-Shan
PS
Department of Microbiology, Soochow University, Taipei, Taiwan, ROC. psliu@scu.edu.tw
Tu
Hung-Yu
HY
Kao
Lung-Sen
LS
D003994:Bucladesine / Q000494:pharmacology; D002110:Caffeine / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D045744:Cell Line, Tumor; D006801:Humans; D009447:Neuroblastoma / Q000378:metabolism* / Q000473:pathology; D010716:Phosphatidylinositols / Q000378:metabolism*
D010716:Phosphatidylinositols; D002110:Caffeine; D003994:Bucladesine; D002118:Calcium