Staurosporine-induced Ca2+ mobilization in rat mandibular salivary acini.
The effect of the protein kinase C inhibitor, staurosporine, on intracellular Ca2+ homeostasis was investigated in rat mandibular salivary acinar cells loaded with fura-2. Fura-2 fluorescence was measured at 510 nm while the excitation wavelength was alternated between 340 nm and 380 nm. The ratio of fluorescence intensity (F(340/380)) was used as an index of [Ca2+]i. Stimulation of acinar cells with 10 microM carbachol (CCh) induced a rapid increase in F(340/380) followed by a slow decrease to a sustained elevated level. Addition of 1 microM staurosporine in the presence of CCh caused a further increase in F(340/380). In order to examine whether the staurosporine-induced increase in F(340/380) could be attributed either to the Ca2+ entry pathway or to the mobilization of Ca2+ from intracellular Ca2+ stores, 1 microM staurosporine was added in the presence of CCh after Ca2+ had been omitted from the perfusate. Even in the absence of extracellular Ca2+, F(340/380) still increased slowly from 0.75 +/- 0.05 to 1.57 +/- 0.24 after a delay ranging between 5 min and 10 min. However, the IP3-sensitive intracellular Ca2+ stores did not seem to play a major role in this phenomenon because staurosporine still increased F(340/380) by 0.6 +/- 0.10 after the complete depletion of IP3-sensitive Ca2+ stores by the exposure of cells to 1 microM thapsigargin, a microsomal Ca2+ ATPase inhibitor, in Ca2+-free conditions. These results suggest that staurosporine mobilizes Ca2+ from IP3-insensitive intracellular Ca2+ stores in rat mandibular salivary acinar cells.
Shin
D M
DM
Dept. Oral Biology, Yonsei University College of Dentistry, Seoul, Korea.
Kim
Y J
YJ
Lee
S I
SI
Seo
J T
JT
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism* / Q000493:pharmacokinetics; D002217:Carbachol / Q000494:pharmacology; D018679:Cholinergic Agonists / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D019311:Staurosporine / Q000494:pharmacology*; D013363:Submandibular Gland / Q000187:drug effects* / Q000378:metabolism*; D019284:Thapsigargin / Q000494:pharmacology
D018679:Cholinergic Agonists; D004791:Enzyme Inhibitors; D019284:Thapsigargin; D015544:Inositol 1,4,5-Trisphosphate; D002217:Carbachol; D019311:Staurosporine; D002118:Calcium