Electrophysiological evidence of degeneration activity in the parotid gland of the rat

Abstract

In the parotid gland of the rat intracellular recordings were made 13–30 hours after section of the auriculo‐temporal nerve or excision of the superior cervical ganglion. Shortlasting membrane potential changes (hyperpolarisation or depolarisation) and resistance decreases, much larger and more frequent than in the control gland, were observed. The degeneration activity after parasympathectomy was blocked by atropine, whereas the sympathetic degeneration activity was blocked by the α‐blocker dihydroergotamine. The electrical activity is thus believed to be due to release of neurotransmitter from degenerating nerve fibres; β‐blockers and tetrodotoxin did not significantly affect the activity.

Electrophysiological effects of substance P and VIP in the denervated rat parotid gland

“…Altogether 104 rats weighing 276-495 g of a Sprague-Dawley strain bred at the Department of Physiology were used. Isolated segments of parotid glands were removed after cervical dislocation and mounted in a small tissue bath ( I ml), continuously superfused by an oxygenated Krebs-Henseleit solution at 37 "C as previously described (Thesleff 1982). Membrane potential and input resistance were recorded using an intracellular double barrel microelectrode filled with 3 M KCI and bevelled to a suitable resistance (5-25 Ma).…”

“…In order to further study the mechanisms behind the apparent supersensitivity, six rats were assessed 20-30 h after parasympathetic denervation. This time was chosen to coincide with the termination of degeneration activity (Delfs & Emmelin 1979, Thesleff 1982, while hypersensitivity to acetylcholine and noradrenaline had not developed. In some of the experiments, where comparisons were made between the denervated and contralateral unoperated glands, segments from both glands were mounted in the same bath and alternating recordings were made.…”

“…The administration of agonist by drops to the bath has been found to give reproducible responses with a short latency rather similar to the responses to nerve stimulation or ionophoresis (Thesleff 1982). This mode of application was thus generally preferred, but comparisons were regularly made with the agonist included in the perfusate to estimate concentration ranges, In this way, the possibility that ionophoresis currents in salivary gland preparations may release endogenous transmittor substances does not have to be taken into account.…”

Proceedings of the Physiological Society, 21‐22 February 1986, Royal Free Meeting: Communications

“…The other system is activated by /8-adrenoceptor agonists, probably also by vasoactive intestinal polypeptide (VIP) and is mediated by the adenylate cyclase/cAMP system, which is not believed to be associated with permeability changes. Previous electrophysiological investigations in vitro, concerning fi-adrenoceptor activation, have shown small membrane potential changes appearing after a long latency (Roberts & Petersen, 1978;Thesleff, 1982).…”