Figure 6. Effects of DIDS on [³H]ryanodine binding to native and purified RyR1s in the presence or absence of aldolase.

Equilibrium [³H]ryanodine binding to native (A) or purified (B) RyR1s was performed as described in the Experimental section in the presence of 10 μM free Ca²⁺ without (□) or with (■) 35 μg/ml aldolase. With purified RyR1, 30 μM DIDS in the presence of 35 μg/ml aldolase induced a greater increase in activity compared with the absence of aldolase. The control is the specific [³H]ryanodine binding in the presence of 10 μM free Ca²⁺ (pH 7.3). Specific [³H]ryanodine binding at the various concentration of DIDS with or without aldolase is expressed as a percentage of the control. *Significantly different between the two experimental groups (unpaired Student's t test, P<0.05). The results are expressed as the means±S.E.M. for 5 independent experiments.