Comparison of neurotoxic effects of tetracaine and ropivacaine on brachial plexus nerve in rats

Abstract

Objective To compare the neurotoxic effects of tetracaine and ropivacaine on the brachial plexus nerve in rats. Methods Forty-eight adult male SD rats weighing 410-430 g were randomly divided into 8 groups ( n = 6 each): group normal saline (group NS), group D1-3 and group R1-4 . The rats in group NS, D1-3 and R1-4 received injection ofO.9% saline 1 ml, 0.25% , 0.5% and 1% tetracaine 0.5 ml, 0.25% , 0.5% and 1% ropivacaine 1 ml, and 2% ropivacaine 0.5 ml respectively through one side of the axillary sheath. The other side was set as the control side. Five days later, the maximum amplitude of brachial plexus nerve action potential and nerve conduction velocity (NCV) of brachial plexus nerve were determined. Results Compared with the control side, the maximum amplitude of nerve action potential and NCV were significantly decreased in group D2-3 and R3-4( P < 0.05). The maximum amplitude of nerve action potential and NCV were significantly decreased in group D2,3 and R3,4 than in group NS (P < 0.05). The maximum amplitude of nerve action potential and NCV were significantly decreased in group D than in group D, ( P < 0.05) . The maximum amplitude of nerve action potential and NCV were significantly decreased in group D3, and the maximum amplitude of nerve action potential and NCV were significantly increased in group R2 than in group D2( P < 0.05) . The maximum amplitude of nerve action potential and NCV were significantly increased in group R3 than in group D3(P< 0.05). The maximum amplitude of nerve action potential and NCV were significantly decreased in group R4 than in group R1-3 ( P < 0.05) .ConclusionEquivalent dose tetracaine has a greater neurotoxicity than ropivaca ine. Key words: Tetracaine; Amides; Brachial plexus; Action potentials