An Electrophysiological Study of Neuroglandular Transmission in the Isolated Salivary Glands of the Cockroach

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Abstract
1. Some aspects of neuroglandular transmission in isolated salivary glands of the cockroach have been studied. 2. The membrane potential of acinar cells is -32.3±0.8 mV (mean±S..E; N = 600 cells) when the gland is bathed in Ringer solution. 3. Upon delivering a single shock by ‘field stimulation’ to the salivary nerves the gland cell membrane undergoes after an initial latency of 1 second a transient hyperpolarization of about 1-30 mV which lasts for about 10 sec. 4. When the salivary nerves are stimulated by trains of current pulses the hyperpolarization that occurs is larger in amplitude and longer in duration than that after a single stimulus. 5. The amplitude of the responses to single shocks and stimulus trains depends on the external potassium concentration. Thus, the neurotransmitter may increase membrane permeability to potassium ions. 6. The electrical response of the gland cell to 5-hydroxytryptamine in concentrations from 2.5-250x10-7 M is similar in sign and magnitude to that of nervous stimulation. 7. Occasionally small fluctuations in the membrane potential are observed and these are similar in sign and duration to responses elicited by single shocks to the salivary nerves.