Is the modality of the supersensitivity after sympathectomy age and duration dependent?

Sympathetic denervation of the rat parotid gland was performed neonatally or in adult fully developed animals on one side. The contralateral gland served as control. Two and 9 weeks later the glands were used for in vitro amylase secretory studies. The neonatally denervated glands displayed an enhanced response to high concentrations of noradrenaline, without significant changes in the lower concentration range. In adult sympathectomized animals no significant alteration could be recorded in secretory response 9 weeks after denervation. Two weeks after adult ganglionectomy a striking leftward shift of the noradrenaline concentration-response curve was observed without changes in the maximal response. Thus, the modality of the supersensitivity appears to be influenced by the age of the animal when the surgical procedure is performed, as well as by the duration of the denervation.