Influence of 2,4 dichlorophenoxyacetate and of dantrolene sodium on the target phenomenon in tenotomized rat gastrocnemius muscle

The influence of traction on the target phenomenon was analysed in the tenotomized gastrocnemius muscle of Wistar rats. Target fibres were constantly observed at the medial side of the heads of the non-immobilized and tenotomized gastrocnemius muscles used as control. In the muscles fixed in flexion, no target fibres could be detected, while in the muscles fixed in hyperextension some target fibres were seen. The latter were less numerous than those present in the non-immobilized muscles. This experiment proves the importance of stretch mechanisms in the pathogenesis of the target phenomenon.

Influence of stretch on the target phenomenon in the tenotomized and immobilized gastrocnemius muscle of the rat

Reuck¹,

Coster²,

Eecken³

1983

Influence of isaxonine on the target phenomenon, muscle fibre size and neuromuscular junction in the tenotomized and denervated gastrocnemius muscle of the rat

Bleecker¹,

Coster²,

Reuck³

et al. 1986

Isaxonine is reported to accelerate the rate of peripheral nerve regeneration, stimulate axonal sprouting and promote motor and sensory function recovery. The target phenomenon in muscle fibers is the morphological expression of increased stretch activity in a diseased muscle. It can be produced in the gastrocnemius muscle of the rat by tenotomy and is inhibited by simultaneous denervation. The influence of isaxonine on this experimental model was studied. Twenty Wistar rats were submitted to bilateral section of the Achilles tendon and section of the left sciatic nerve. In ten rats, treated with isaxonine, the qualitative and quantitative changes in the gastrocnemius muscle were compared with the control group over a period of 3 weeks. No statistical differences were observed in the occurrence and inhibition of the target phenomenon, the muscle fibre size and the neuromuscular junction. Isaxonine has no direct effect on a diseased muscle with an intact nerve supply, nor in the early stages after complete denervation.

Inhibition of the target phenomenon in tenotomized rabbit muscle by medullary lesions

Reuck¹,

Coster²,

Potter³

et al. 1982

Target fibres were demonstrated in the gastrocnemius muscles following section of the Achilles tendon of two rabbits. In five other animals with tenotomized gastrocnemius muscles, a subarachnoid phenol block of the lumbar and sacral spinal cord was performed. Large and small medullary lesions inhibited the occurrence of target fibres in the tenotomized muscles, the smallest one being neurolysis of the dorsal roots. This final experiment suggests that the target phenomenon is the morphological expression of an increased stretch sensitivity of the tenotomized muscle.