[3H]9-Methyl-7-bromoeudistomin D, a caffeine-like powerful Ca2+ releaser, binds to caffeine-binding sites distinct from the ryanodine receptors in brain microsomes

Abstract[3H]9-Methyl-7-bromoeudistomin D ([3H]MBED), the most powerful Ca2+ releaser from sarcoplasmic reticulum, specifically bound to the brain microsomes. Caffeine competitively inhibited [3H]MBED binding. [3H]MBED binding was markedly blocked by procaine, whereas that was enhanced by adenosine-5′-(β,γ-methylene)triphosphate. The Bmax value was 170 times more than that of [3H]ryanodine binding. The profile of sucrose-density gradient centrifugation of solubilized microsomes indicated that [3H]MBED binding protein was different from [3H]ryanodine binding protein. These results suggest that there are MBED/caffeine-binding sites in brain that are distinct from the ryanodine receptor and that MBED becomes an essential molecular probe for characterizing caffeine-binding protein in the central nervous system

Measurement and Estimation of the Particle Size Distribution by the Buoyancy Weighing-Bar Method and the Rosin-Rammler Equation

Measuring the size distribution of fine particles (<5 µm) in a few hours is difficult when using the sedimentation method due to a decrease in sedimentation rate. Herein, we discussed the validity of using a combination of the buoyancy weighing–bar method and the Rosin–Rammler equation to estimate the particle size distribution. When the cumulative mass oversize exceeds about 0.15, the Rosin–Rammler equation can be used to estimate the particle size distributions of suspended solids