Sensitivity of the nictitating membrane of the cat to succinylcholine after decentralization and denervation.

Seven days after decentralization or denervation, the nictitating membrane of the cat becomes supersensitive to succinylcholine. The supersensitivity to succinylcholine is of a moderate degree (2-3 fold) and there is little difference between the supersensitivity induced by decentralization or denervation. In this respect, it is similar to the decentralization type of supersensitivity observed for other agonists which are not taken up by the adrenergic nerve endings (e.g. acetylcholine and methoxamine). Since succinyloholine causes an apparent contraction of the nictitating membrane through its action on the extraocular muscle and no effect on the nictitating membrane itself, it is concluded that both chronic decentralization and denervation produced a decentralization type supersensitivity in the extraocular muscles. The results suggest that supersensitivity in the extraocular muscles may contribute significantly to the decentralization supersensitivity of the nictitating membrane of the cat, in vivo, especially for those agonists which cause contractions of both the nictitating membrane and the extraocular muscle.