SUBCELLULAR DISTRIBUTION OF 5-HYDROXYTRYPTAMINE IN THE RABBIT BRAIN

抄録

1. Employing the centrifugal fractionation method, the particulate 5-HT of rabbit brain was chiefly found in the heavier granules of crude mitochondrial fraction as well as in the microsomal particles. The higher 5-HT content of microvesicle fraction reported by WHITTAKER is attributable to his omitting the acetone extraction procedure, the activity observed by him being mainly that of substance P.
2. Such a particulate 5-HT was released by raising temperature, lowering pH, lowering osmotic pressure and by treating with ether, acetone or with higher concentration of KCl, while other cations such as Na⁺, Ca⁺⁺ and Mg⁺⁺ showed hardly any effect up to 200mM. Reserpine caused loss of particulate 5-HT in about 40% for 4 hours.
3. The particulate 5-HT is susceptible to monoamine oxidase, which seems to destroy it nearly completely when incubated at 37°C.
4. The 5-HT-containing granules show hardly any uptake of 5-HT added to the suspension media at 4°C.
5. In the microsomal fraction, a 5-HT-inactivating action is proved, which disappears after boiling and is inhibited by iproniazid, but not so activated with ether as reported by WHITTAKER.