Effect of extracellular magnesium on secretagogue-evoked amylase secretion in the isolated rat parotid gland segments.

This study investigates the effect of perturbation of extracellular magnesium [Mg2+]o on basal and acetylcholine (ACh), noradrenaline (NA) and phenylephrine (PHE)-evoked amylase secretion from isolated rat parotid gland segments. Both zero (0 mM) and elevated (5 mM and 10 mM) [Mg2+]o can significantly (P < 0.05) inhibit basal and secretagogue-evoked amylase secretion compared to the responses obtained in normal (1.1 mM) [Mg2+]o. The inhibitory effect of zero [Mg2+]o was more pronounced compared 10 mM [Mg2+]o. A concentration of 5 mM, [Mg2+]o was less effective at a secretagogue concentration of 10(-5) M but more pronounced in inhibiting amylase secretion when the concentration of the secretagogue was reduced to 10(-6) M. The results indicate that both hypo and hypermagnesaemia are associated with reduced salivary amylase secretion and both conditions may be associated with 'the dry mouth syndrome'.