Effects of 2,4-dichlorophenoxyacetic acid (2,4-D) on the contractile properties of reinnervated rat skeletal muscle.
2,4-Dichlorophenoxyacetic acid (2,4-D), a common herbicide, was administered to rats (100 mg/kg, i.p.) during 24 days to determine whether or not it is toxic to regenerating peripheral nerve and reinnervating muscle. The peroneal nerve was crushed 1 cm proximal to the extensor digitorum longus muscle and recordings made in vivo after 1 to 24 days. Functional reinnervation was observed by day 10 and recovery was similar in rats receiving 2,4-D or vehicle. Distal motor latencies and muscle action potentials returned toward normal during the 24 days in a similar manner in 2,4-D and controls. Isometric twitch tensions per muscle weight on indirect stimulation returned to intact values by 17 days, but in the 2,4-D animals they became larger (P less than 0.01) than controls by day 24. The twitch:tetanus ratios were increased at day 10 and returned toward normal values in the controls but remained increased (P less than 0.01) in the 2,4-D animals at 24 days. Similar results were obtained on direct muscle stimulation. The data suggest that 2,4-D is not toxic to nerve during regeneration or muscle reinnervation in the rat, but that it does affect both twitch and tetanus tensions suggesting proliferation as well as disruption of myofibrils.
D015084:2,4-Dichlorophenoxyacetic Acid / Q000494:pharmacology*; D000818:Animals; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009132:Muscles / Q000294:innervation*; D009416:Nerve Regeneration / Q000187:drug effects; D010525:Peripheral Nerves / Q000187:drug effects; D051381:Rats; D011916:Rats, Inbred F344
D015084:2,4-Dichlorophenoxyacetic Acid