Electrophysiology of mouse parotid acini: effects of electrical field stimulation and ionophoresis of neurotransmitters.

Abstract

SUMMARY1. Intracellular micro-electrode recordings of membrane potential and input resistance were made from surface acini of mouse parotid glands placed in a Perspex tissue bath through which oxygenated physiological saline solutions were circulated. The acinar cells were stimulated by microionophoresis of both acetylcholine (ACh) and adrenaline (Ad) from extracellular micropipettes, and by electrical field stimulation via a pair of platinum electrodes.2. The acinar cells had a mean resting membrane potential of -64x9 mV + 0x6 s.E. The input resistance of the unstimulated cell was 4-63 MQ + 0419 S.E. In a number of cells spontaneous miniature depolarizations were observed, associated with synchronous reductions in input resistance.3. The responses to ionophoresis of both ACh and Ad and the response to supramaximal field stimulation were identical. Stimulation always evoked a marked decrease in input resistance associated with an initial potential change, generally followed by a delayed hyperpolarization during which the input resistance returned to normal.4. Field-stimulation responses could be evoked to single shock (1-2 msec) and to low frequency (1-4 Hz) stimulation. The latency for this response was 245 (10-5 M) abolished the response to Ad but left the field-stimulation response unaffected.8. Electrical field stimulation of isolated segments of salivary gland evoked release of endogenous neurotransmitter as a consequence of neural excitation. The technique of field stimulation thus makes it possible to investigate the functional innervation of a gland using the in vitro preparation. In the mouse parotid gland the field stimulus response was mediated by ACh released from parasympathetic nerve endings.

Substance P is a functional neurotransmitter in the rat parotid gland.

“…In this as in previous studies (Gallacher & Petersen, 1980b) (Gallacher & Peterson, 1980 respective agonists in this tissue (Rudich &r Butcher, 1976;Gallacher &;Petersen, 1980b) revealed that both cholinergic and adrenergic mechanisms were involved in the field stimulus-evoked amylase release (Fig. 3).…”

“…All micro-electrodes were filled with 3 M-KCl+10 M-K citrate and had tip resistances of 10-30 MCI. Electrical field stimulation was achieved via a pair of fine platinum electrodes brought into light contact with the tissue as previously described (Gallacher & Petersen, 1980b).…”

“…Recently however the techniques of radioimmunoassay and immunohistochemistry have demonstrated substance P-like immunoreactivity localized within the varicosities of nerves in salivary glands including the rat parotid gland (Hokfelt, Johansson, Kellerth, Ljungdahl, Nilsson, Nygards & Pernow, 1977; Robinson, Schwartz & Costa, 1980;Brodin & Nilsson, 1981). Additionally, Nishiyama, Katoh, Saitoh & Wakui (1980) and Gallacher & Petersen (1980b) have demonstrated that the technique of electrical field stimulation is an effective means of stimulating the nerves of the isolated salivary gland preparation. In this study the technique of field stimulation was employed to excite the intrinsic nerves of the isolated rat parotid gland to investigate the role of the intrinsic nerves in activation of acinar cells, in particular to investigate the possibility that a functional non-cholinergic, non-adrenergic innervation exists in this tissue.…”

Activation of Ca2+-dependent Cl- and K+ conductances in rat and mouse parotid acinar cells.

“…Conventional microelectrode studies of mouse parotid gland acinar cells have shown that the autonomic nerve stimulation, as well as the application of acetylcholine (ACh) or adrenaline, increases the membrane con-ductance primarily to K+ but also to other ions (RoBERTS et al, 1978;GALLACHER and PETERSEN, 1980). The recent patch-clamp single channel current recordings have shown that Cat-and voltage-activated K+ channels, with a large unit conductance, dominate in the basolateral membrane in these glands (MARUYAMA et al, 1983a).…”

Proceedings of the Physiological Society, 11‐12 November 1983, Queen Elizabeth College, London Meeting: Communications

“…In this study the technique of electrical field stimulation (FS) was used (Gallacher & Petersen, 1980;Gallacher, 1983) to investigate for the first time the role of the intrinsic nerves in the activation of beta-adrenoceptor mechanisms in the isolated rat parotid gland. Parotid segments were superfused with physiological saline solutions containing atropine (10-5 M) and phentolamine (10-5 M).…”