The rate of release of acetylcholine from the in vitro superior cervical ganglion of the rat was measured during periods of electrical stimulation both before and after exposure to a drug. Cytochalasin B inhibited the release of acetylcholine in this preparation. Two stages of inhibition were observed. The first, which reduced the rate of release to 20% of control values, was produced by incubating the ganglion for 60 min in solutions containing cytochalasin B. Half-maximal inhibition was observed at concentrations of 3 × 10-6M. This stage was not reversed within several hr after cytochalasin B was removed. Uptake of calcium in the first stage was inhibited by cytochalasin B by a small but statistically insignificant amount (13%). The second stage, in which release was further reduced to zero, required both repeated changes of bathing solutions containing cytochalasin B and continual electrical stimulation during the 60 min period of exposure. The second stage was reversed 20-40 min after the drug was removed. It is suggested that the first stage inhibition involves a direct action of cytochalasin B upon the release of acetylcholine from the presynaptic terminal, while the second stage inhibition may be caused by a decrease in the supply of energy to the ganglion. Vinblastine at concentrations of 2.0 × 10-6and 1.2 × 10-4M was also studied using the same experimental procedure. Vinblastine did not inhibit the electrically stimulated release of acetylcholine. © 1974.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below