Effect Of Parasympathetic Denervation Research Articles

Expression and Trans-synaptic Regulation of P2x4 and P2z Receptors for Extracellular ATP in Parotid Acinar Cells: EFFECTS OF PARASYMPATHETIC DENERVATION

Trans-synaptic regulation of muscarinic, peptidergic, and purinergic responses after denervation has been reported previously in rat parotid acinar cells (McMillian, M. K., Soltoff, S. P., Cantley, L. C., Rudel, R., and Talamo, B. R. (1993) Br. J. Pharmacol. 108, 453-461). Characteristics of the ATP-mediated responses and the effects of parasympathetic denervation were further analyzed through assay of Ca2+ influx, using fluorescence ratio imaging methods, and by analysis of P2x receptor expression. ATP activates both a high affinity and a low affinity response with properties corresponding to the recently described P2x4 and the P2z (P2x7)-type purinoceptors, respectively. Reverse transcription-polymerase chain reaction analysis reveals mRNA for P2x4 as well as P2x7 subtypes but not P2x1, P2x2, P2x3, P2x5, or P2x6. P2x4 protein also is detected by Western blotting. Distribution of the two types of ATP receptor responses on individual cells was stochastic, with both high and low affinity responses on some cells, and only a single type of response on others. Sensitivity to P2x4-type activation also varied even among cells responsive to low concentrations of ATP. Parasympathetic denervation greatly enhanced responses, tripling the proportion of acinar cells with a P2x4-type response and increasing the fraction of highly sensitive cells by 7-fold. Moreover, P2x4 mRNA is significantly increased following parasympathetic denervation. These data indicate that sensitivity to ATP is modulated by neurotransmission at parasympathetic synapses, at least in part through increased expression of P2x4 mRNA, and suggest that similar regulation may occur at other sites in the nervous system where P2x4 receptors are widely expressed.

Effect of parasympathetic denervation on K + release by rat parotid slices

1. By measuring the release of 86Rb, potassium movement was compared in parasympathectomized (Px) and contralateral control parotid gland slices three weeks following surgical denervation. 2. Carbachol and phenylephrine elicited a biphasic increase in 86Rb release that was dose related and could be blocked by atropine and phentolamine respectively. The transient phase was of 2–4 min duration and Ca independent whereas the sustained phase of 86Rb release was greatly reduced by the omission of the external Ca. 3. Denervation caused a shift to the left of the 86Rb efflux dose-response curve to carbachol and phenylephrine (3.75- and 3.37-fold respectively). Pilocarpine had similar action to carbachol but it behaved as a partial agonist. 4. Parasympathectomy (Px) increased the intrinsic activity of the partial agonist pilocarpine and converted it to a full agonist. Results of the present study indicate the possibility of an altered receptor-signal transduction mechanism between the receptor and phospholipid turnover/Ca mobilization in the denervated rat parotid gland.

The effects of tympanic neurectomy and chorda tympanectomy on experimentally induced parotid duct fistulae in rabbits.

To study the effects of parasympathetic denervation on the secretory activity of parotid fistulae, polyethylene catheters were introduced bilaterally into the parotid main excretory ducts of 10 rabbits, followed by unilateral parasympathectomy performed by segmental resection of the tympanic plexus and the chorda tympani nerve. Although salivary flow from the fistulae of the denervated parotid glands stopped up to 8 days earlier than that from the healthy (control) glands, the effect of parasympathectomy was not strong enough to recommend this operation as the method of choice for the clinical inactivation of persistent parotid fistulae.

Effect of parasympathetic denervation on acetylcholine levels in the rat parotid gland. Is there an extraneuronal pool of acetylcholine?

Parasympathetic denervation of the rat parotid gland by avulsion of the auriculotemporal nerve caused a marked and lasting decrease in gland weight. Parasympathectomy did not change the levels of choline in the gland but decreased by 60% the levels of acetylcholine (ACh) ten days after surgery and 65% at 28 days. It is puzzling that relatively high levels of ACh remained after parasympathetic denervation. The presence of additional cholinergic nerves that innervate the gland, or pass through it en route to other structures may account for some of the remaining ACh. Also, Schwann cells from denervated nerves might have contributed to some of the ACh. The existence of an extraneuronal source of ACh is considered.

Non-specific supersensitivity in rat parotid salivary glands following parasympathectomy.

1 The effect of parasympathetic denervation (Px) of the rat parotid salivary glands has been studied. 2 Px produced a significant reduction in wet and dry weight of the parotid gland compared with the intact contralateral control gland. The DNA content per gland was not reduced indicating that cell death had not occurred but that individual cells were smaller. 3 Supersensitivity to both cholinoreceptor and beta-adrenoreceptor stimulation resulted following Px and was observed as a decrease in the threshold dose and an increase in the maximum secretory response. 4 The supersensitivity to beta-adrenoreceptor stimulation was not accompanied by a change in cyclic AMP production but there was an increase in the density of beta-adrenoreceptor binding sites/mg membrane protein. 5 The relationship of this increased density of receptors to the observed supersensitivity is discussed.

Effect of parasympathetic denervation on oxidative phosphorylation and adenosine-triphosphatase activity of mitochondria in the left and right ventricles of dogs

Effect of parasympathetic denervation on oxidative phosphorylation and adenosine-triphosphatase activity of mitochondria in the left and right ventricles of dogs

The problem of the effect of parasympathetic denervation on the protein metabolism of the submaxillary salivary glands of the cat

The author studied the influence of unilateral and bilateral section of the chorda tympani on the protein metabolism and the secretory function of the submaxillary salivary glands in cats. The reflex and the “paralytic” secretion in the denervated glands was absent. The nitrogen content of mucin in the tissues of these glands increased.

Secretory Function of the Stomach After Denervating Operations

The acid secretory function of the stomach was observed in ulcer patients with intact stomachs and in patients after three types of operative procedures. After those operations which caused interruption of parasympathetic innervation there was only slight increase in volume after histamine and there was a decrease in the volume of secretion during insulin hypoglycemia. After both types of stimulation, the concentration of secreted chloride increased. It is suggested that one of the major effects of histamine is on the vascular system of the stomach and that an important effect of parasympathetic denervation is the interruption of reflex arcs which normally permit vasodilatation in response to stimulation. Submitted on May 13, 1957

Effect of Parasympathetic Denervation on Feline Bladder Function

Effect of Parasympathetic Denervation on Feline Bladder Function