Muscarinic signalling in submandibular salivary acinar cells of ageing rats.

Muscarinic cholinergic stimulation of submandibular acinar cells results in the activation of Ca(2+)-dependent ion-transport pathways responsible for the secretion of primary saliva. Decreased saliva production is common among elderly people and may compromise oral health with implications for systemic health, nutrition, and quality of life. The density and affinity of muscarinic receptors in the submandibular gland of rats and the Ca2+ responses to stimulation of these receptors in the acinar cells were examined. An increase in the number of receptors and increases in the affinities of the receptors were found as the rats age from 7 weeks to 11 months. However, the coupling of the receptors to the intracellular Ca2+ signals in acinar cell clusters was substantially reduced in the older animals.