Somatic effectors are dependent on their innervation to maintain structural and functional integrity. When denervated, they eventually atrophy. This is the fate of denervated voluntary muscles as noted in lower motor paralysis. Autonomic effectors are not wholly dependent on their innervation. Denervated involuntary muscles, cardiac muscle, and glands continue to function. For example the transplanted heart might function reasonably well. However, when deprived of autonomic nervous system influences, these effectors are abnormal in that they do not respond as effectively as they should to satisfy the changing demands of the organism.
When an effector is deprived of it's innervation, it may become extremely sensitive to chemical mediators (neurotransmiters)...
Denervation hypersensitivity is noticeable in clinical situations following sympathectomy. In Horner's syndrome, the pupil of one eye is constricted and does not normally dilate because it is deprived of sympathetic stimulaiton. However, when a patient with a Horner's syndrome is extremely excited, the epinephrine and norephinephrine released by the adrenal medulla can stimulate the hypersensitive denervated dilator muscle or the iris to respond sot htat the pupil dilates; this is known as the paradoxical pupillary resonse.
page 368
The Human Nervous System: Structure and Function
Charles R. Noback, David A. Ruggiero, Robert J. Demarest, Norman L. Strominger
sixth edition
Humana Press
