Atropine-resistant secretion of parotid saliva on stimulation of the auriculo-temporal nerve.

Non-adrenergic non-cholinergic parasympathetic secretory responses in parotid glands of rats have been demonstrated by electrical stimulation of the auriculo-temporal nerve after appropriate blocking drugs and compared with secretion in the absence of these drugs. After atropine +/- adrenergic blocking drugs secretion was greatly reduced but some secretion was always evident at frequencies of 5 Hz and higher. The time taken for secretion to appear was greatly increased and this may relate to an absence of accompanying myoepithelial contraction. Continuous stimulation always produced greater flows of saliva than intermittent bursts of stimulation at higher frequencies both in the absence and in the presence of blocking drugs. Thus it is likely in vivo that secretion is induced by relatively steady nerve-impulse traffic at moderate frequencies rather than by bursts of high frequency stimulation. Possible transmitters contributing to the atropine-resistant secretion are considered.