T-type calcium channel expression in cultured human neuroblastoma cells

Human neuroblastoma cells （SH-SY5Y） have similar structures and functions as neural cells and have been frequently used for cell culture studies of neural cell functions.Previous studies have revealed L-and N-type calcium channels in SH-SY5Y cells.However,the distribution of the low-voltage activated calcium channel （namely called T-type calcium channel,including Cav3.1,Cav3.2,and Cav3.3） in SH-SY5Y cells remains poorly understood.The present study detected mRNA and protein expres-sion of the T-type calcium channel （Cav3.1,Cav3.2,and Cav3.3） in cultured SH-SY5Y cells using real-time polymerase chain reaction （PCR） and western blot analysis.Results revealed mRNA and protein expression from all three T-type calcium channel subtypes in SH-SY5Y cells.Moreover,Cav3.1 was the predominant T-type calcium channel subtype in SH-SY5Y cells.

FRACTIONAL TIME SCALE IN CALCIUM ION CHANNELS MODEL

We propose a fractional time scale to model the calcium ion channels model which is retarded with injection of calcium-chelator Ethylene Glycol Tetraacetic Acid （EGTA）. By using this nonlinear time scale and Modified Riemann-Liouville fractional derivative, we convert the integer-order calcium ion channels model into fractional-order differential equations. We also analyze the range of order of fractional-order differentiM equations to ensure the equilibria of it are asymptotically stable. The simulation results are given to demonstrate the solutions of this model coincide with the real experiment data.

A novel ω-conotoxin Bu8 inhibiting N-type voltage-gated calcium channels displays potent analgesic activity

ω-Conotoxins inhibit N-type voltage-gated calcium(Ca_(v)2.2)channels and exhibit efficacy in attenuating neuropathic pain but have a low therapeutic index.Here,we synthesized and characterized a novelω-conotoxin,Bu8 from Conus bullatus,which consists of 25 amino acid residues and three disulfide bridges.Bu8 selectively and potently inhibits depolarization-activated Ba^(2+ )currents mediated by rat Ca_(v)2.2 expressed in HEK293 T cells(IC_(50)=89 nmol/L).Bu8 is two-fold more potent thanω-conotoxin MVIIA,aω-conotoxin currently used for the treatment of severe chronic pain.It also displays potent analgesic activity in animal pain models of hot plate and acetic acid writhing but has fewer side effects on mouse motor function and lower toxicity in goldfish.Its lower side effects may be attributed to its faster binding rate and higher recovery ratios.The NMR structure demonstrates that Bu8 contains a small irregular tripleβ-strand.The structure-activity relationships of Bu8 Ala mutants and Bu8/MVIIA hybrid mutants demonstrate that the binding mode of Ca_(v)2.2 with the amino acid residues in loop 1 and loop 2 of Bu8 is different from that of MVIIA.This study characterizes a novel,more potentω-conotoxin and provides new insights for designing Ca_(v)2.2 antagonists.