Secretory potentials in the sublingual gland of the cat.

Summary. The sublingual gland of the cat has been used for electrophysiological measurement of the external current flow as well as intracellular potentials and the potential of the lumen of the gland cell tubules at rest and during activity. The external chorda electrogram is hilus-negative. After passing through an initial maximum, it declines to about half its maximal size, often displaying slow oscillations. Also the external sympathetic electrogram is hilus-negative. Only one type of microelectrode response was encountered in this gland. The resting potential over the outer gland cell membrane is about 33 mV (internal negativity). On stimulation of the chorda this potential difference increases to 50–65 mV, the latency of the potential change being about 1 second and the rate of rise 30–40 mV/sec. The latency as well as the initial time-course of this potential change is similar to that of the initial phase of the external chorda electrogram. Also with stimulation of the sympathetic nerve the potential difference over the outer membrane increases. The resting potential over the inner gland cell membrane is a few mV larger than over the outer membrane (cell interior negative). On repetitive stimulation of the chorda there is initially little or no potential change, but with continued stimulation the potential difference over the inner membrane usually, but not always, increases by 10–15 mV. The potential change recorded between the lumen and the external medium has a time-course similar to that of the external electrogram.