Sensitization of the rat parotid gland to secretagogues following either parasympathetic denervation or sympathetic denervation or decentralization.

The sensitivity of the rat parotid gland to chemical agents was examined 2--3 weeks after either parasympathetic denervation or sympathetic denervation or decentralization. The parasympathetically denervated gland was markedly sensitized towards methacholine; a nonspecific supersensitivity mainly mediated via alpha-adrenoceptors was also demonstrated. The sympathetically denervated gland had developed a supersensitivity which was both of the pre- and the postjunctional type; it was predominantly of the former type to noradrenaline and adrenaline, and entirely so to phenylephrine; it was of the latter type to isoprenaline, and also to methacholine. The sympathetically decentralized gland was mainly sensitized towards noradrenaline, adrenaline and isoprenaline. The postjunctional supersensitivity developed towards the sympathomimetic drugs after sympathetic decentralization was of about the same magnitude as that observed after sympathetic denervation; this type of supersensitivity was mainly mediated via beta-adrenoceptors.