Effects of capsaicin on Ca(2+) release from the intracellular Ca(2+) stores in the dorsal root ganglion cells of adult rats.
We have investigated the effect of capsaicin on Ca(2+) release from the intracellular calcium stores. Intracellular calcium concentration ([Ca(2+)](i)) was measured in rat dorsal root ganglion (DRG) neurons using microfluorimetry with fura-2 indicator. Brief application of capsaicin (1 microM) elevated [Ca(2+)](i) in Ca(2+)-free solution. Capsaicin-induced [Ca(2+)](i) transient in Ca(2+)-free solution was evoked in a dose-dependent manner. Resiniferatoxin, an analogue of capsaicin, also raised [Ca(2+)](i) in Ca(2+)-free solution. Capsazepine, an antagonist of capsaicin receptor, completely blocked the capsaicin-induced [Ca(2+)](i) transient. Caffeine completely abolished capsaicin-induced [Ca(2+)](i) transient. Dantrolene sodium and ruthenium red, antagonists of the ryanodine receptor, blocked the effect of capsaicin on [Ca(2+)](i). However, capsaicin-induced [Ca(2+)](i) transient was not affected by 2-APB, a membrane-permeable IP(3) receptor antagonist. Furthermore, depletion of IP(3)-sensitive Ca(2+) stores by bradykinin and phospholipase C inhibitors, neomycin, and U-73122, did not block capsaicin-induced [Ca(2+)](i) transient. In conclusion, capsaicin increases [Ca(2+)](i) through Ca(2+) release from ryanodine-sensitive Ca(2+) stores, but not from IP(3)-sensitive Ca(2+) stores in addition to Ca(2+) entry through capsaicin-activated nonselective cation channel in rat DRG neurons.
Eun
S Y
SY
Department of Physiology, Department of Biophysics, Seoul National University College of Medicine, 28 Yongon-dong, Chongno-gu, Seoul, 110-799, Korea.
Jung
S J
SJ
Park
Y K
YK
Kwak
J
J
Kim
S J
SJ
Kim
J
J
D000818:Animals; D001920:Bradykinin / Q000494:pharmacology; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels; D002211:Capsaicin / Q000031:analogs & derivatives* / Q000494:pharmacology*; D002478:Cells, Cultured; D003592:Cytophotometry; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005456:Fluorescent Dyes; D016257:Fura-2; D005727:Ganglia, Spinal / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007424:Intracellular Fluid / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018160:Receptors, Cytoplasmic and Nuclear / Q000037:antagonists & inhibitors; D011955:Receptors, Drug / Q000037:antagonists & inhibitors; D019837:Ryanodine Receptor Calcium Release Channel / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors
D015220:Calcium Channels; D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; D053496:Inositol 1,4,5-Trisphosphate Receptors; D018160:Receptors, Cytoplasmic and Nuclear; D011955:Receptors, Drug; D019837:Ryanodine Receptor Calcium Release Channel; D002110:Caffeine; D010738:Type C Phospholipases; C071423:capsazepine; D002211:Capsaicin; D001920:Bradykinin; D002118:Calcium; D016257:Fura-2