The Effects Of Intrathecal Levobupivacaine On The Spinal Cord In Rats

Objectives: Levobupivacaine is a new long-acting amide local anaesthetic. The aim of this study was to observe the ultramicrostructure of spinal cord, nerve roots after spinal anesthesia with polyurethane microspinal catheters(P E-10) administration of different desity and dose Levobupivacaine in SD rats.Methods: (1) 18 male SD rats weighting 280-320 g were anesthetized with intraperitoneal 10% Chloral Hydrate 300 mg/Kg,A polyurethane microcatheter was inserted into the lumbar subarachnoid space according to the technique described by yan jian ping. An 2 cm catheter segment was left in subarachnoid space, the animals was randomly to dedived into 3 groups to intrathecal(IT) normal saline,0.5％or 0.75 %Levobupivacaine40μl。6 hours after the intrathecal(IT) adminstration the animals was decapitated and L1 spinal cord with both anterior and posterior roots were excised for light and electron microscopic examination and Ca2+ content determination. (2) 18 male SD rats randomized to devide into4 groups and to receive normal saline,0.5 % or 0.75 % Levobupivacaine 40μl intrathecally every 2 hours for 3 times, 24 hours after the intrathecal(IT) adminstration the animals was decapitated and L1 spinal cord with both anterior and posterior roots and dorsal ganglion as well as cauda equina were excised for light and electron microscopic examination and Ca2+ content determination. Results: Electron microscope revealed neurolemma of the nerve root and mitochondria and endoplasmic reticulum of the neurons in spinal cord was intact in group A1,A2 and Bl。Some reversible changes were found in B2 group.Conclusions: 0.75 % Levobupivacaine has neurotoxicity to spinal cord intrathecally continuous.