Eosinophil cationic protein and myeloperoxidase in nasal secretion as markers of inflammation in allergic rhinitis

The inflammatory component of allergic rhinitis was studied by measuring the concentration and content of eosinophil cationic protein (ECP, specific for eosinophils) and myeloperoxidase (MPO, specific for neutrophils) in samples of nasal secretion from 20 pollen-allergic subjects. All secretion samples contained measurable concentrations of both proteins. The mean ECP concentrations on two occasions without pollen exposure were 950 and 1170 micrograms/l. The ECP concentration during the pollen season without any therapy (mean 1160 micrograms/l) did not differ significantly from the baseline values, but intranasal corticosteroid therapy resulted in a significant decrease (mean 530 micrograms/l). The concentration of MPO was about 10 times higher than that of ECP, but the changes in MPO were nonsignificant throughout the observation period. An inverse correlation was found between the threshold dose in histamine challenges and the ECP level expressed either as concentration or as content. Furthermore, the ECP concentration and content 1 day after a positive allergen challenge were both significantly correlated with the strength of the challenge reaction. Measurements of ECP in nasal secretions are useful for studying the presence and activity of eosinophils in the nasal mucosa, and may prove of value in clinical investigations on patients with allergic rhinitis.     

Comparison of the effects of 2-deoxyglucose and immobilization on secretion and synthesis rate of catecholamines in the adrenal gland: a microdialysis study in conscious rats

Using microdialysis, extracellular 3,4-dihydroxyphenylalanine (DOPA), noradrenaline (NA) and adrenaline (AD) concentrations in the adrenal gland were monitored in conscious rats during and after 60 min of immobilization (IMM) as well as after injection of 500 mg kg^-1 2-deoxyglucose (2-DG). IMM produced a rapid and transient increase in secretion of AD (20-fold), NA (13-fold) and DOPA (3.6-fold). This was accompanied by an increase in blood pressure (+ 18 mmHg) and heart rate (- 146 b. p.m.). Repeated exposure to IMM (daily 60 min, for 5 days) had no influence on either catecholamine secretion of haemodynamic profiles, indicating the lack of habituation to stressful conditions. Unlike IMM, the stress of 2-DG-induced centralneuroglucopenia stimulated the release of AD without affecting NA secretion. AD levels peaked (5.1-fold increase) 4&60 min after 2-DG injection and then slowly declined. 2-DG induced no changes in blood pressure but reduced the heart rate (-48 b. p.m.). In separate experiments, steady-state dialysate DOPA levels, reached during continuous infusion of decarboxylase inhibitor NSD 1015 into adrenal gland tissue through the dialysis probe, served as an index of adrenomedullary tyrosine hydroxylase (TH) activity. IMM evoked a marked increase in TH activity (DOPA formation increased 2.7-fold), which remained elevated 60 min after the cessation of stress when AD and NA secretion had already fallen to baseline. After 2-DG, despite significant hormonal response, adrenal TH activity was unchanged. These results give clear evidence that IMM and 2-DG-induced neuroglucopenia may be considered as two different types of stressful stimuli.     

Dependency of renal potassium excretion on Na,K-ATPase transport rate

Potassium secretion may depend on the transport rate of Na, K-ATPase in basolateral cell membranes of distal tubular cells. To examine this hypothesis experiments were performed in anaesthetized dogs during inhibition of proximal potassium reabsorption by acetazolamide or mannitol (fractional potassium excretion 1.2-1.4) or additional stimulation of potassium secretion by ethacrynic acid (fractional potassium excretion 2.1). Ouabain in a dose which inhibits 70–80% of the Na, K-ATPase activity reduced fractional potassium excretion to 0.8-0.9 by an effect on distal tubular secretion since potassium transport in the proximal tubules was not affected. Ouabain-sensitive potassium excretion varied in proportion to ouabain-sensitive sodium reabsorption during variation in glomerular nitration rate, even at urinary sodium concentrations exceeding 80 mmol 1^-1. In experiments without ouabain, saline infusion raised potassium excretion and sodium reabsorption until maximal Na, K-ATPase transport rate was reached, as judged from heat production measurements, but not during further increments in urine flow. After inhibition of Na, K-ATPase activity by hypokalaemia, potassium excretion and cortical heat production remained constant over a wide range of urine flow and sodium excretion. We conclude that potassium secretion is dependent on intact Na, K-ATPase activity and is stimulated by sodium delivery to the distal nephron until maximal transport rate of the enzyme is reached.     

Changes in element concentrations induced by agonist in pig pancreatic acinar cells

 Changes in electrolytes of pig pancreatic acinar cells following application of gastrin-cholecystokinin (CCK) were investigated using the technique of X-ray microanalysis of hydrated and dehydrated sections of freshly frozen pancreas. After stimulation by CCK (10^–9 M), Na and Cl increased significantly in the cytoplasm [Na, from 10 mmol/kg wet wt. (48 mmol/kg dry wt.) to 19 mmol/kg (95 mmol/kg); Cl, from 22 mmol/kg (105 mmol/kg) to 49 mmol/kg (245 mmol/kg)] as well as in the luminal interspace [Na, from 53 mmol/kg (189 mmol/kg) to 65 mmol/kg (283 mmol/kg); Cl, from 65 mmol/kg (232 mmol/kg) to 102 mmol/kg (443 mmol/kg)]. In the secretory granules Cl increased significantly from 30 mmol/kg (86 mmol/kg) to 67 mmol/kg (203 mmol/kg). K decreased significantly from 120 mmol/kg (571 mmol/kg) to 81 mmol/kg (405 mmol/kg) in the cytoplasm, while both increased from 38 mmol/kg (109 mmol/kg) to 58 mmol/kg (176 mmol/kg) in the granules and from 46 mmol/kg (164 mmol/kg) to 48 mmol/kg (209 mmol/kg) in the luminal interspace. Ca increased significantly in the cytoplasm as well as in the luminal interspace, and decreased significantly in the secretory granules. CCK evoked Ca release from secretory granules in the secretory pole of acinar cells. The values were measured from dehydrated sections, and agreed well with those from hydrated sections. The effect of furosemide, an inhibitor of the Na⁺-K⁺-2Cl^–co-transporter, on the ion transport of acinar cell was studied. When furosemide (10^–5 M) was added to the external solution, the cytoplasmic Cl and Ca concentrations decreased significantly, while there was a little decrease in Na and K concentrations under the secretory condition. These results indicate that Na⁺-K⁺-2Cl^–co-transport, and Na⁺, Cl^–and K⁺ exits into the lumen are involved in the mechanism of ion secretion in pig pancreatic acinar cells. Received: 17 January 1996 / Accepted: 12 March 1996     

Histamine concentrations in nasal secretion and secretory activity in allergic rhinitis

The prerequisites for using the assayed histamine concentration in nasal secretion as an objective measure of disease activity in allergic rhinitis were investigated. It was demonstrated that in histamine determination procedures the presence of quenching substances in the nasal secretion could lead to underestimation of the histamine concentration. This bias was eliminated in a modified spectrofluorometric assay. Only an insignificant fraction of the histamine in samples collected by nasal spray washing was bound to unfiltrable particles or cells. The mean histamine concentration in nasal secretions from 15 healthy subjects was 11.2 micrograms/ml and in a group of nine patients with allergic rhinitis out of season 3.36 micrograms/ml. The histamine concentration in the latter group decreased during the pollen season and after positive allergen challenge. It is suggested that this decrease is caused by the increase in volume of the secretion during the allergic response. The use of lithium as an exogenous marker permitted quantitation of the increase in the relative amount of nasal secretion recovered by washing in the symptomatic subjects.     

Modeling of stimulation–secretion coupling in a chromaffin cell

We constructed a chromaffin cell model for analysis of stimulation–secretion coupling in computer simulation studies. The model includes mechanisms involved in the excitatory synapse, voltage-dependent Na⁺, K⁺ and Ca²⁺ channels, Ca²⁺-activated K⁺ channels (SK type), buffered Ca²⁺ diffusion, Ca²⁺ extrusion, fluorescent Ca²⁺ indicators and Ca²⁺-triggered exocytosis. Calculations of the modeled mechanisms were carried out using the NEURON simulation environment (Hines and Carnevale, Neural Computation 9:1179–1209, 1997). A set of parameter values was determined so as to fit basic experimental results reported in the literature. The model was also applied to simulate our experimental results obtained from chromaffin cells in the perfused rat adrenal medulla. Observed profiles of Ca²⁺responses induced by electrically stimulating the splanchnic nerve with various frequencies (1–50 Hz) were adequately simulated with minor readjustments of parameter values for Ca²⁺influx and extrusion. Secretory responses measured at the same time as the Ca²⁺responses were also simulated with consideration of a time constant to detect catecholamines in the experiment. Similarly, model simulations reproduced both Ca²⁺responses and secretory responses evoked by elevations of the extracellular K⁺ concentration for different periods. The results suggest that the presented model provides a useful tool for analyzing and predicting quantitative relations in various events occurring in stimulation–secretion coupling in chromaffin cells.     

Tetraethylammonium-insetisitive,Ca2+-activated whole-cell K+ currents in rat submandibular acinar cells

Using whole-cell patch-clamp techniques, we demonstrate, for the first time, that rat submandibular acinar cells contain a tetraethylammonium (TEA)-insensitive, Ca²⁺-activated K⁺ conductance which is not attributable to large conductance, voltage-sensitive, Ca²⁺-dependent K⁺ channels (maxi-K⁺ channels). Taken together with our recent K⁺ efflux and fluid secretion studies in intact rat submandibular gland, we postulate that the K⁺ conductance reported here may be involved in the basolateral K⁺ efflux pathway activated by cytosolic Ca²⁺ concentration during secretion by this gland.     

Secretin dissipates red aridine orange fluoescence from pancreatic duct epithelium

This study was undertaken to elucidate whether duct cells in the pancreas contain acidic cytoplasmic compartments regulated by secretion. Microdissected pancreatic ducts from pigs were examined by acridibe orange (AO) and 2′, 7′-biscarboxyethyl-5(6)-carboxyfluorescein/tetraacetioxymethyl ester (BCECF/AM) epifluorescence microscopy. Estimated cytoplasmic pH using BCECF fluorescence was 7.43pL0.04 and was not changed by altering CO₂ tension in the incubation mdium. The epithelium of acridine orange incbated peripheral interlobular pancreatic ducts exhibited green and fluorescence was sen in resting pancreatic ducts and was greatly accentuated by raising CO₂ in the incubation medium with chloroqyuine or NH₄Cl or the protonophores carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP) or carbonyl cyanide M-chlorophenylhydrazone (CCCP), leaving uniform gren fluoresence. These findings suggest that pancreatic duct cells contain CO₂-dependent acidic compartments which vanishduring seceatin stimulation and which may be cytoplasmic tubulovesicles.     

Effects of guanabenz and guanfacine on postsynaptic α2-adrenoceptors in the rat submaxillary and parotid glands

Summary The effects of two ₂-agonists (guanfacine and guanabenz) on both the submaxillary and parotid gland of the rat were studied. Whereas guanfacine in doses ranging between 1,000 and 30,000 g/kg i.v. produced an immediate and persistent secretion of saliva from the submaxillary gland, guanabenz in doses as high as 40,000 g/kg did not induce measurable secretion either from the parotid or the submaxillary gland. Secretion clicited by guanfacine was not modified by yohimbine (300 g/kg) but was abolished by prazosin (100 g/kg).In both glands, low doses of either guanabenz (10 g/kg) or guanfacine (100 g/kg) markedly inhibited the secretory responses induced by noradrenaline, methacholine and substance P, but not that induced by isoprenaline. The inhibition caused by the ₂-agonists was greater for noradrenaline than for either methacholine or substance P. Blockade of ₂-adrenoceptors with yohimbine (300 g/kg) did not modify the response to noradrenaline, methacholine or substance P in either gland. However, the same dose of yohimbine injected 5 min before the ₂-agonists prevented the inhibitory effects of guanfacine and guanabenz on the response induced by either one of the three sialagogic agents. Guanabenz (10 g/kg) did not modify the increase in mean blood pressure observed after the different doses of noradrenaline employed to induce salivary secretion. Guanabenz (10 g/kg) and guanfacine (100 g/kg) did not change the time course of the secretion elicited by either noradrenaline, methacholine or substance P, since the degree of inhibition was of similar magnitude at all the periods of time analyzed.The results obtained give further support to the hypothesis that activation of ₂-adrenoceptors in the submaxillary as well as parotid gland of the rat inhibits secretory responses which are mediated by either muscarine, substance P and ₁-receptors and not those elicited by -adrenoceptors.Partially supported by grants no. 3111 k/83 CONICET and Res 40-5/4/84 SUBCYT     

Cholinergic control of gastric acid secretion

Summary In the perfused stomach preparation of the anaesthetized rat the cholinergic agonists acetylcholine (ACh) and bethanechol stimulated gastric acid secretion. Both agonists produced similar maximal acid output (70 mol/15 min) when infused intravenously. However, bethanechol was more potent, eliciting half maximal stimulation at 1.98 mol/kg/h. Secretory responses to either agonist were antagonized in a dose related fashion by blockade of muscarinic receptors with atropine. In contrast, inhibition of nicotinic receptors with hexamethonium produced a striking potentiation of ACh stimulated secretion whilst the bethanechol elicited secretion remained unaffected. In the presence of full nicotinic receptor blockade the ACh response curve was shifted to the left sixfold, half maximal stimulation being produced at 1.79 mol/kg/h. Cimetidine partially inhibited the secretory responses elicited by either ACh or bethanechol while blockade of adrenoceptors ( and ) did not affect acid output induced by cholinergic agonists. Secretion elicited by ACh is interpreted as being the composite effect of prosecretory action and an inhibitory mechanism due to the activation of nicotinic receptors. Hexamethonium, through nicotinic receptor blockade, inhibits the restricting mechanism and thus reveals the full stimulatory action of ACh.