[Neuronal impulse activity in surviving sections of the guinea pig neocortex during blockade of synaptic transmission by adenosine].

Background neuronal discharges were recorded extracellularly in guinea pig cerebral cortex slices maintained in vitro. Synaptic disconnection was reached by adding 100 microM of adenosine or 20-75 microM of 5-AMP. It was shown that 30-40% of neurons continued to discharge even under conditions of complete synaptic blockade, although the discharge frequency decreased. These neurons were considered as endogenously active ones. Other cells stopped their activity as soon as adenosine reached the slice, but they began to generate action potentials again after superfusion with normal solution. These cells were synaptically activated and were considered as exogenously active. In particular most cells with initially very regular discharges became silent during blockade and restored their activity after superfusion with normal saline. This fact suggests the existence of reverberating activity in neocortical slices with periods of 30-140 ms.