The effects of vasoconstrictor on transmission of impulses in the peripheral nerve

The effects of extraneural and intramuscular applications of l-adrenaline on peripheral nerve function were examined. Change in the compound action potential was monitored until a complete conduction block was obtained if it occurred within 100 min. Extraneural application of 0.5 ml l-adrenaline to an isolated segment of the sciatic nerve of the rat in three concentrations of 1:100,000; 1:10,000, and 1:2,000 resulted in complete conduction block within 8 min. However, intramuscular injections of similar concentrations resulted in concentration dependent neural blockades with the highest concentration causing conduction blockade in 27.1 +/- 8.0 min.