The effect of tri-o-cresyl phosphate (TOCP) and methamidophos (MET) on potassium-stimulated 45Ca uptake by brain synaptosomes in hens was studied. An in vivo test showed that TOCP increased potassium-stimulated calcium uptake 2 h after its administration, but that verapamil suppressed the enhancement of this calcium uptake. An in vitro test showed that lower concentrations of TOCP stimulated calcium uptake by synaptosomes, but that higher concentrations inhibited the uptake. In contrast, all tested concentrations of MET obviously inhibited calcium uptake; however, since calcium uptake was decreased by the administration of verapamil plus either TOCP or MET, the mechanism by which TOCP affects the voltage-operated calcium channel may be different from that of MET. The disruption of calcium homeostasis may be involved in organophosphate-induced delayed neurotoxicity (OPIDN). Calcium channel blocker may ameliorate OPIDN by maintaining calcium homeostasis in nerve cells.
Bibliographical noteFunding Information:
This project was supported by grants from the National Nature Science Foundation of China (No. 39970151), CAS Innovation Program (KSCX1-SW-13-02-04; KSCX3-IOZ-04) and the CAS Life Sciences Special Fund (supported by the Ministry of Finance) (STZ98-2-13). Authors thank Dr. Carey Pope for helpful comments on earlier draft, and Dr. Ron Moorhouse for polishing the English.
Copyright 2017 Elsevier B.V., All rights reserved.
- Calcium uptake
- Methamidophos (MET)
- Organophosphate-induced delayed neurotoxicity (OPIDN)
- Tri-o-cresyl phosphate (TOCP)