A methodological study of spinal (subarachnoid) anaesthesia in the rat and the mouse

Rat and mouse were utilized as models to study the spinal (subarachnoid) anesthetic effects of five commonly used local anaesthetic agents. Duration and frequency of motor and sensory blockade, and onset time were determined after injection of 5.0% lignocaine, 0.75% bupivacaine and 1.0% amethocaine to the same groups of rats with chronically implanted catheters in the lumbar subarachnoid space. Dose-response curves for lignocaine, mepivacaine, bupivacaine, amethocaine and cinchocaine were obtained after single intrathecal injection to the mouse. The relative potency and other characteristics of the compounds investigated were in agreement with results obtained in other species, including man. The techniques described may provide useful adjuncts to methods in larger animals for the evaluation of potential new spinal anaesthetic agents, and the study of various factors that may influence spinal anaesthesia.