Can 4-chloro-m-cresol be substituted for caffeine as an activator of calcium oscillation in bullfrog sympathetic ganglion cells?
4-Chloro-m-cresol (cresol) and caffeine have been shown to be potent activators of the Ca(2+) release mediated by the ryanodine-sensitive Ca(2+) release channel and therefore increase the cytosolic free calcium concentration in skeletal muscles. To distinguish the effects of cresol and caffeine in neurones, the responses of the intracellular ([Ca(2+)](i)) and intraluminal free calcium concentrations to cresol were investigated using bullfrog sympathetic ganglion cells and then compared with those to caffeine. Cresol generated a gradual rise (slow response) with and without a fast transient rise (fast response) in [Ca(2+)](i). A low extracellular Ca(2+) concentration abolished the slow response but not the fast response, thus indicating that the slow response was caused by a Ca(2+) influx across the cell membrane. The fast response was inhibited by ryanodine, thus confirming that the source may therefore be the Ca(2+) release through the ryanodine-sensitive calcium store. Unlike caffeine, the long-term application of cresol did not cause any calcium oscillation; neither did it cause a decrease in the basal calcium levels.
Higure
Yoko
Y
Division of Instrumental Analysis, Analytical Research Center for Experimental Sciences, Saga University, Nabeshima, Saga 849-8501, Japan.
Shimazaki
Yuka
Y
Nohmi
Mitsuo
M
D000818:Animals; D002110:Caffeine / Q000378:metabolism / Q000494:pharmacology*; D020013:Calcium Signaling / Q000187:drug effects*; D002478:Cells, Cultured; D003408:Cresols / Q000378:metabolism / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005728:Ganglia, Sympathetic / Q000187:drug effects / Q000378:metabolism*; D011892:Rana catesbeiana; D012433:Ryanodine / Q000378:metabolism / Q000494:pharmacology
D003408:Cresols; D012433:Ryanodine; C006984:chlorocresol; D002110:Caffeine