Figure 5

Glutamate induces Ca²⁺ influx via both glutamate receptors and voltage-gated Ca²⁺ channels in third-order neurons. (A) Glutamate-induced [Ca²⁺]_i is completely blocked by ionotropic glutamate receptor antagonists, CNQX (50µM) and AP-7(40µM). (B) Co²⁺ blocks voltage-gated Ca²⁺ channels, which reduces 55% of glutamate-induced [Ca²⁺]_i in the neurons (see asterisk); with Co²⁺ taurine still suppresses glutamate-induced [Ca²⁺]_i. (C) Ruthenium red (1µM), a rynadine receptor inhibitor, reduces 15% of glutamate-induced [Ca²⁺]_i; with ruthenium red, taurine has 35% suppression on glutamate-induced [Ca²⁺]_i in the neurons. (D) Blocking Ca²⁺ uptake pumps in the internal organelles with thapsigargin (1µM) had a limited effect on taurine regulation of [Ca²⁺]_i.