Myoepithelial cell activation in the submaxillary salivary gland

1. Pressure in the duct of the submaxillary gland of the cat was recorded under chloralose anaesthesia. Single pulses applied to the parasympathetic nerve caused a pressure rise.2. Salivation was just detectable in about half of the animals when an open tube was connected to the duct and single pulses applied to the nerve. Applying a back pressure of 1-4 mm Hg renders the duct less distensible and under these circumstances secretion of 1-3 mul. fluid was always seen. An alternative method of detecting salivation based on the pressure record itself also showed that salivation occurred in response to the stimulus and that salivation was responsible for the pressure rise observed.3. Single pulses applied to the cervical sympathetic trunk produced a small fall in pressure. In a short series of pulses this was followed by a slow rise which then slowly decayed. It was tentatively concluded that the initial fall was secondary to the accompanying vasoconstriction but the subsequent effects were due to myoepithelial cell contraction.4. Close arterial injection of bradykinin caused a pressure rise which could best be explained by myoepithelial cell contraction.5. It is concluded that the myoepithelial cells of the submaxillary gland of the cat do not receive a parasympathetic motor innervation but it is probable that they are innervated by the sympathetic nervous system and contract in the presence of bradykinin.