Effects of cytochalasin B on uptake and release of putative transmitters by synaptosomes and on brain actomyosin-like protein

A LARGE variety of contractile cellular functions is thought to be associated with microfilamentous processes which can be disrupted by the fungal metabolite cytochalasin B (ref. 1). To this list of contractile processes have been added the stimulated release of secretory products^2-4 as well as transmitter agents⁵. Based in part on the isolation of actomyosin-like protein (neurostenin) from mammalian brain nerve ending preparations⁶ a mechanism has been suggested for the exocytotic release of transmitter materials at synaptic endings involving contractile events similar to those occurring during muscle contraction⁷. We have examined the effect of cytochalasin B on the uptake by Rat whole brain nerve ending preparations of noradrenaline, dopamine, glutamic acid and GABA and their K⁺-stimulated release. We also studied the effect of cytochalasin B on the adenosine triphosphatase activity of the brain actomyosin-like protein and muscle actomyosin.