Figure 7.

Neither glucose-6-phosphate nor thapsigargin cause release of ⁴⁵Ca²⁺ from rat brain ER microsomes. After pre-loading ER microsomes with radiotracer ⁴⁵Ca²⁺ uptake for 45 min, glucose-6-phosphate (10 mM), thapsigargin (1 μM), or the calcium ionophore A23187 (10 μM) treatment was added for 15 min. Only A23187 caused release of ⁴⁵Ca²⁺ from the rat brain microsomes when measured by beta counter. Both glucose-6-phosphate and thapsigargin reduced the rate of accumulation, but did not cause release. Data are means ± SEM for n = 7.