IN VITRO INVESTIGATION OF THE PRIMING PRINCIPLE FOR RAPID NEUROMUSCULAR BLOCK

The priming principle was investigated in the rat phrenic nerve-diaphragmpreparation stimulated continuously at 0.2 Hz. Tubocurarinewas added to the organ bath as either a single (non-primed)or a divided (primed) dose. Priming consisted of 15% or 20%of the final dose, with priming intervals of 5 or 10 min. Primingdecreased significantly the time to 80% block and was associatedwith mild neuromuscular block. A simple model adequately predictedthe time to 50% and 80% block, using the same diffusion constantfor both primed and non-primed conditions. The onset of neuromuscularblock, with and without priming, depended mostly upon the distributionof the drug to its site(s) of action. Present address: Department of Anesthesiology, The Johns HopkinsHospital Baltimore, Md, U.S.A. Accepted for Publication: October3, 1988.