BAPTA-AM and Dibromo BAPTA-AM both decrease the amplitude of EPSPs in the crayfish neuromuscular junction, but have minimal effect on synaptic facilitation

Abstract

The relationship between internal calcium and the processes of EPSP generation and synaptic facilitation is not fully understood. We explored this relationship by reducing the internal calcium with the chelators BAPTA-AM and Dibromo BAPTA-AM. Two different chelators were used because they have different affinities for calcium and might have different effects on the two processes we are studying. Our results show calcium chelation to have a significantly depressing effect on EPSP generation but display no such trend on synaptic facilitation. This suggests different sensitivities of the two processes to calcium chelation, perhaps because the chelation has little or no effect on the amount of residual calcium found in the cell after synaptic activation. No significant difference was observe between BAPTA-AM and Dibromo BAPTA-AM, thus, the difference in affinity of the chelators was not great enough to create a marked difference in either process.