[The effects of chloride channel blockers on thrombocytic cytoplasmic free calcium concentration and platelet aggregation].
OBJECTIVE
To explore the effects of chloride channels on the regulation of platelet cytoplasmic free calcium concentration ([Ca2+]i) and platelet aggregation (PAG).


METHODS
Freshly separated platelets were activated by thrombin. Chloride channel blockers DIDS or NFA and calcium channel blockers SK&F96365 or nifedipine were added to study the effects on platelet [Ca2+]i and PAG by a single reagent or the combination of reagents and find out the interactions among DIDS, NFA, SK&F96365 and nifedipine.


RESULTS
Both DIDS and NFA could inhibit the thrombin (1 U/ml) induced PAG in a dose-dependent manner, whereas had little effect on resting [Ca2+]i. As compared with the control group, DIDS, SK&F96365 and Nifedipine could significantly reduce the PAG, Ca2+ release and Ca2+ influx in thrombin activated platelet (P < 0.05). The combination of DIDS and SK&F96365 had greater effects in reducing the PAG, Ca2+ release and Ca2+ influx than either reagent alone (P < 0.05). The combination of DIDS and nifedipine also had greater effect than each alone in reducing Ca2+ release (P < 0.05). The combination of NFA and SK&F96365 weakened each other's effect on Ca2+ release (P < 0.05), while NFA and nifedipine weakened each other's effects on PAG, Ca2+ release and Ca2+ influx in thrombin activated platelet (P < 0.05).


CONCLUSIONS
DIDS and NFA have no effect on the resting [Ca2+]i and the leak calcium influx of platelet. DIDS can inhibit the Ca2+ release, Ca2+ influx and PAG of platelet induced by thrombin, while NFA can only inhibit the Ca2+ release. The chloride channel and calcium channel blockers have interactions in affecting resting [Ca2+]i and PAG of platelet. The opening of chloride channel can influence the cellular calcium movement of platelet.
Yin
Song-Mei
SM
Department of Hematology, The Second Affiliated Hospital of SunYat-sen University, Guangzhou 510120, China.
Chen
Xiao-Lin
XL
Nie
Da-Nian
DN
Xie
Shuang-feng
SF
Ma
Li-ping
LP
Wang
Xiu-ju
XJ
Wu
Yu-dan
YD
Li
Yi-qing
YQ
Feng
Jian-hong
JH
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology*; D000328:Adult; D001792:Blood Platelets / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002478:Cells, Cultured; D018118:Chloride Channels / Q000037:antagonists & inhibitors / Q000502:physiology; D003593:Cytoplasm / Q000187:drug effects / Q000378:metabolism; D004347:Drug Interactions; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D009543:Nifedipine / Q000494:pharmacology; D009544:Niflumic Acid / Q000494:pharmacology*; D010974:Platelet Aggregation / Q000187:drug effects*; D013917:Thrombin / Q000494:pharmacology
D002121:Calcium Channel Blockers; D018118:Chloride Channels; D007093:Imidazoles; D009544:Niflumic Acid; D013917:Thrombin; C063159:1-(2-(3-(4-methoxyphenyl)propoxy)-4-methoxyphenylethyl)-1H-imidazole; D009543:Nifedipine; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D002118:Calcium