Rat parotid glands develop extensively in the 3 weeks following birth, acquiring sympathetic and parasympathetic innervation as well as secretory function.The relationship of receptor acquisition to maturation was studied.Muscarinic and /%adrenergic receptors in rat parotid have been characterized and their appearance during development measured using the specific ligands (3H]quinucIidinyl benzilate (QNB) and ['251]iodohydroxybenzyl pindolol (Kyp), respectively.Scatchard analysis of saturation curves for adult membranes gave dissociation constants (KD) and receptor densities of 105 2 11 PM and 126.1 st 8.0 fmol/mg of membrane protein for QNB (n = 6) and 157 & 17 PM and 98.1 f 6.3 fmol/mg of membrane protein for HYP (n = 5 ) .The KD determined for QNB is dependent on receptor concentration in the binding assay.QNB binding is selectively blocked by muscarinic ligands.The pharmacology of the '251-HYP binding site is appropriate to PI-type receptors.In immature animals, the KD for each ligand is the same as for adults.Binding of QNB and HYP is detectable at birth, and reaches adult density at around 25 days.Isoproterenol-sensitive adenylate cyclase activity and amylase secretion have been reported to be refractory to stimulation until after 8 to 13 days (Grand, R.
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Ludford et al. (1980) studied this question.
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