Cytochalasin blocks sympathetic ganglionic transmission: a presynaptic effect antagonized by pyruvate.

The mold metabolite cytochalasin B blocked transmission through the perfused superior cervical sympathetic ganglion of the cat. Acetylcholine injected close-arterially during block continued to excite the ganglion cells so that failure was presynaptic and, by inference, due to reduced output of acetylcholine from the preganglionic nerves. This blocking effect of cytochalasin was reduced by pyruvate. It is concluded that cytochalasin inhibits cholinergic nervous function and it does so, at least in part, by depressing energy production at some stage before pyruvate formation. One possibility is a block of glucose uptake for which there is evidence from other cell types. A more general conclusion is that inhibitory effects of cytochalasin on other secretory systems may also involve such a metabolic component and do not necessarily reflect an interaction of the drug with microfilaments as has been commonly supposed.