THE EFFECT OF DENERVATION ON THE SENSITIVITY TO ADRENINE OF THE SMOOTH MUSCLE IN THE NICTITATING MEMBRANE OF THE CAT

Abstract

The isotonic and isometric responses of the smooth muscle of the cat''s nictitating membrane to standard doses of adrenine injected in-traven. were recorded immediately after sympathetic denervation and at frequent intervals thereafter (every 2-3 days) until no further change was observed. After removal of the superior cervical ganglion, the magnitude of response of the corresponding nictitating membrane to the same dose of adrenine increases rapidly during the first 6-8 days, and more gradually during the next 6-8 days, after which further change is slight. The increase of response as a result of decentralization (section of the cervical sympathetic nerve) bears the same time relations, but the extent of the increase is ca. 1/2 as great aa after denervation. After removal of the decentralized ganglion a 2d increase of response occurs, and the final level of responsiveness attained is ca. equal to that obtained by denervation without previous decentralization. Of the various theories advanced by previous authors to explain the phenomenon of sensitization after denervation, the recent hypothesis of Rosenblueth that a change in permeability occurs in smooth muscle as a result of denervation is considered the most satisfactory.