Figure 2.

Distribution of cADPR-induced Ca²⁺ release among cauliflower microsomal subfractions. Vesicles from each fraction were preloaded with Ca²⁺ and potential further uptake following Ca²⁺ release subsequently inhibited as detailed in “Materials and Methods.” An aliquot was removed for radioactivity counting and cADPR (1 μm) was then added. Three aliquots were removed successively over the ensuing 2 min to measure changes in accumulated Ca²⁺. Results are the means ± se of three to six replicates from two different membrane preparations. Stars indicate non-detectable uptake.