Sympathetic nerves and nasal secretion in the cat

Sympathetic nerve stimulation influences mucociliary activity in the rabbit maxillary sinus

The effect of preganglionic sympathetic nerve stimulation on mucociliary activity in the rabbit maxillary sinus was investigated in vivo. Response to nerve stimulation was recorded photoelectrically and expressed as a percentage of the basal mucociliary activity prior to stimulation. Nerve stimulation (15 V, 5 ms) for 60 s at 2, 10 and 20 Hz stimulated mucociliary activity, the maximum increase being 21.1 +/- 1.3% at 20 Hz, an increase that pretreatment with the cholinergic antagonist atropine reduced to 14.5 +/- 2.4%, suggesting that part of the response involves cholinergic mechanisms. Nerve stimulation (10 Hz) of animals pretreated with the beta-adrenoceptor antagonist propranolol reversed the mucociliary response from an increase to a decrease (-10.6 +/- 1.6%), indicating the involvement of beta-receptors in the nerve-evoked increase. Pretreatment with the alpha-adrenoceptor antagonist phentolamine had no effect on response to nerve stimulation. Rabbits given a combined atropine, propranolol and phentolamine blockade manifested decreased mucociliary activity in response to nerve stimulation (-10.6 +/- 2.1%). Guanethidine pretreatment blocked the effect of nerve stimulation on mucociliary activity, including the observed decrease after combined blockade, indicating the effect to be mediated via sympathetic nerve fibres. The decrease in mucociliary activity in response to nerve stimulation after combined cholinergic-, beta-, and alpha-adrenoceptor blockade suggests the presence of a nonadrenergic, non-cholinergic inhibitory mechanism. It is possible that this effect is mediated by release of neuropeptide Y, as intraarterial injections of neuropeptide Y reduce mucociliary activity in the rabbit maxillary sinus, and as neuropeptide Y is released in the upper airways upon sympathetic nerve stimulation.

The secretory activity of rat nasal glands and the effect of cholinergic drugs

The secretory behaviour of rat nasal glands, under normal conditions and after the application of cholinergic drugs, has been studied using morphological and radiobiochemical techniques. Autoradiography and electrophoresis provide evidence for the selective incorporation of 3H-arginine into the glycoprotein-containing fraction of the nasal glandular secretion. Radiobiochemical experiments show that labelled arginine is rapidly incorporated into the acinar cells of unstimulated glands, although it takes approximately 4 h before the labelled secretory proteins leave the cells. The secretion of proteins is stimulated by the parasympathetic agonist pilocarpine, whose main action is to promote discharge. Histological sections show a depletion of secretory granules after pilocarpine treatment. The cholinergic antagonist atropine inhibits the secretion; the acinar cells are completely filled with secretory granules following this treatment. The time course of the events following atropine administration suggests that there is no feed-back system controlling glycoprotein synthesis. The techniques employed here therefore appear to be useful for studying the effects of drugs that interfere with the secretory activity of the nasal glands.

Control of mucoglycoprotein output from the rabbit nose

A method for the collection of rabbit nasal washings to analyse outputs of mucous glycoproteins is described. The radiolabels sodium [35S]sulphate and [3H]glucose are bound to the glycoproteins. The release of bound 35S and 3H was enhanced by cervical sympathetic nerve stimulation. Adrenoceptor agonists (phenylephrine, dobutamine and salbutamol) given I.V. increased the output of 35S, and the last two drugs increased the output of 3H. The blocking effects of thymoxamine and propranolol on these responses are described. Pilocarpine (given I.V. or intranasally) produced large increases in 35S release; histamine had little effect. Irritants (ammonia and cigarette smoke) and diluted serum or plasma, given intranasally, produced large increases in 3H output, and sometimes enhanced 35S release. Radiolabelled nasal washings fractionated on Sepharose CL-4B gel chromatography columns formed two peaks, with most of the radioactivity in the high molecular weight (mucous glycoprotein) peak.

alpha-Adrenoceptor-mediated secretion from the anterior nasal glands of the dog

The secretion of fluid from the anterior nasal glands in pentobarbital-anesthetized dogs was measured by absorption on filter papers that were weighed before and after insertion into the nose. The secretion was stimulated by the local effects of drugs present on the dried filter paper. Methacholine evoked a dose-related secretion that could be reduced by atropine. Phenylephrine caused a scanty but measurable secretion in a dose that is used in topical nasal decongestants. When this alpha-adrenoceptor-stimulating drug was tested in combination with different doses of methacholine, a large increase in secretion was obtained over that with methacholine used alone. The increased secretion evoked by the combination was abolished by the alpha-adrenoceptor blocking drug phentolamine.