Secretory responses to sympathetic stimulation of the cat's salivary glands in a state of resting secretion.

The secretory effect of sympathetic stimulation on the cat's submaxillary gland was augmented greatly when studied against a background of slow secretion evoked by parasympathetic stimulation at a low frequency and imitating the slow resting secretion normally present in the waking state. The sympathetic secretory threshold was markedly lowered, and even at low frequencies sympathetic stimulation caused a large, well-maintained response. After an alpha-adrenoceptor blocking drug sympathetic stimulation alone lost its secretory effect, but during resting secretion part of the accelerating effect was found to remain; this effect was elicited via beta-adrenoceptors. A marked secretory effect of sympathetic stimulation was also obtained during resting secretion in the parotid gland, where the sympathetic secretory effect is normally very small.