The membrane of catecholamine storage vesicles of adrenal medulla catecholamine fluxes and ATPase activity

Abstract

1. A method of preparing isolated membranes of the catecholamine storing vesicles of the adrenal medulla is described. The membrane protein amounts to 23% of the total vesicular protein and still contains 0.1% of the catecholamine. 2. At 31‡C in the presence of ATP the membrane preparation accumulates catecholamine; in the absence of ATP, however, catecholamine is released into the medium. At 0‡C the catecholamine content of the membrane preparation remains unchanged, whether ATP is present or not, although a low catecholamine turnover is observed. 3. From the kinetics of the catecholamine turnover in the absence or presence of ATP a low ATP-independent catecholamine influx can be distinguished from a considerably higher ATP-dependent influx of catecholamine. 4. The catecholamine influx as well as the ATPase activity of the membrane preparation decreases with time; in contrast, the catecholamine efflux remains constant and is higher in the presence of ATP than in its absence. 5. Catecholamine is to a great extent accumulated within a membrane-enclosed space into newly formed particles; only a minor amount of the catecholamines is actually bound within the membrane

Effects of Anticonvulsant and Convulsant Drugs on the Atpase Activities of Synaptosomes and Their Components

“…The uptake process appears to be one of active transport, but the pH-dependence of the process suggests that it may not be linked directly to Mg++-ATPase activity (Taugner, 1971;Phillips, 1974). This work does not have a direct bearing upon the relationship between vesicle Mg++-ATPase and transmitter uptake and release in the central nervous system but it does suggest the processes may be related.…”

Uptake Processes for Biogenic Amines

“…The uptake of catecholamines is stoichiometrically related to a breakdown of A TP in the external medium (Kirshner et al, 1966), but there is no indication that A TP accompanies the catecholamine into the veside. Taugner (1971Taugner ( , 1972 has shown that amine uptake by medullary vesides is probably associated with a Mg 2 +-dependent ATPase in the veside membrane, which can be inhibited by sulfhydryl reagents (see below).…”

Phosphoryl Group Transfer by a Fraction of the Soluble Proteins of Catecholamine Storage Vesicles

“…All procedures were carried out at 2-4°C. Purified catecholamine storage vesicles were obtained by density gradient centrifugation, essentially as described for the preparation of isolated membranes (Taugner, 1971). The vesicles which sedimented in 1.8 M-sucrose were lysed in 60 ml of 15 mM unbuffered KCI.…”