Slow rise of intracellular Ca(2+) concentration in rat primary sensory neurons triggered by loureirin B.
In the present study, the intracellular free calcium concentration ([Ca(2+)](i)) in acutely isolated rat dorsal root ganglia (DRG) neurons modulated by loureirin B, an active component of "dragon's blood" which is a kind of Chinese herbal medicine, was determined by the means of Fura-2 based microfluorimetry. It was found that loureirin B could evoke the elevation of [Ca(2+)](i) in a dose-dependent manner. However, the elevation of [Ca(2+)](i) evoked in the calcium free solution was much smaller than that in the standard external cell solution, suggesting that most change of [Ca(2+)](i) was generated by the influx of extracellular Ca(2+), not by the activities of intracellular organelles like Ca(2+) stores and mitochondria. In addition, the mixture of loureirin B and caffeine also induced [Ca(2+)](i) rise, but the peak of [Ca(2+)](i) rise induced by the mixture was significantly lower than that by caffeine alone, which means the triggering pathway and the targets of caffeine are probably involved in loureirin B-induced [Ca(2+)](i) rise. Moreover, compared to the transients induced by caffeine, KCl and capsaicin, the loureirin B-induced [Ca(2+)](i) rise is much slower and more stable. These results indicate that the capability of loureirin B of inducing the [Ca(2+)](i) rise is solid and unique.
Shanghai University, Shanghai, China.
Yi-Ning
YN
Yang
Jue-Xu
JX
Chen
Xue-Yan
XY
Pang
Susumu
S
Terakawa
Xu
X
Chen
Yong-Hua
YH
Ji
Ke-Lan
KL
Yong
D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D005727:Ganglia, Spinal / Q000187:drug effects / Q000378:metabolism; D009475:Neurons, Afferent / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D012116:Resins, Plant / Q000494:pharmacology*
D012116:Resins, Plant; D002110:Caffeine; C505764:loureirin B; D002118:Calcium