Epithelium-dependent effect of L-glutamate on airways: involvement of prostaglandins.

We investigated the effect of the excitatory amino acid (EAA) receptor agonists L-glutamate, N-methyl-D-aspartate (NMDA), (RS)-a-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) and kainic acid on KCl-induced contractions of rabbit tracheal smooth muscle, as well as the role of epithelium and endogenously produced nitric oxide and prostaglandins on these responses. L-Glutamate decreased KCI-induced contractions up to 30%. This effect was attenuated by epithelium removal, tetrodotoxin, methylene blue and indomethacin but not by NG-nitro-L-arginine methyl ester. While NMDA, AMPA and kainic acid had no effect, the combination of NMDA + kainic acid decreased KCI-induced contractions. These results suggest that, in rabbit trachea, L-glutamate has, at least in part, an epithelium-dependent effect mediated via prostaglandin formation and that the EAA receptors involved are non-classical

Resting Tension Affects eNOS Activity in a Calcium-Dependent Way in Airways

The alteration of resting tension (RT) from 0.5 g to 2.5 g increased significantly airway smooth muscle contractions induced by acetylcholine (ACh) in rabbit trachea. The decrease in extracellular calcium concentration [Ca2+]o from 2 mM to 0.2 mM reduced ACh-induced contractions only at 2.5 g RT with no effect at 0.5 g RT. The nonselective inhibitor of nitric oxide synthase (NOS), NG-nitro-L-arginine methyl ester (L-NAME) increased ACh-induced contractions at 2.5 g RT. The inhibitor of inducible NOS, S-methylsothiourea or neuronal NOS, 7-nitroindazole had no effect. At 2.5 g RT, the reduction of [Ca2+]o from 2 mM to 0.2 mM abolished the effect of L-NAME on ACh-induced contractions. The NO precursor L-arginine or the tyrosine kinase inhibitors erbstatin A and genistein had no effect on ACh-induced contractions obtained at 2.5 g RT. Our results suggest that in airways, RT affects ACh-induced contractions by modulating the activity of epithelial NOS in a calcium-dependent, tyrosine-phosphorylation-independent way

Pulmonary Function and Circulating Adhesion Molecules in Patients with Diabetes Mellitus

BACKGROUND: Lung function in diabetes has been reported in several studies with contradictory results. Diabetes mellitus increases expression of adhesion molecules through hyperglycemia. These molecules play an important role in the pathophysiological dysfunction of the vasculature

Concentration-effect curves for acetylcholine, performed in Krebs solution with low calcium concentration, at an RT of 0

<p><b>Copyright information:</b></p><p>Taken from "Resting Tension Affects eNOS Activity in a Calcium-Dependent Way in Airways"</p><p></p><p>Mediators of Inflammation 2007;2007():-.</p><p>Published online 28 Mar 2007</p><p>PMCID:PMC1868075.</p><p></p>5 g (a) and 2.5 g (b). Data are means and vertical lines show SE. refers to the number of animals studied

Pleural electrophysiology variations according to location in pleural cavity

The aim of the study was to compare the electrophysiology profile of sheep pleura originated from different locations of the pleural cavity with the respective profile in humans. Sheep specimens obtained from upper and lower lung lobes, 1st-4th and 8th-12th rib, ventral-dorsal diaphragm and mediastinum were mounted between Ussing chambers. Human visceral tissues were obtained from patients subjected to lobectomy. Trans-mesothelial resistance (R™) was determined as an indicator of the tissue permeability, while amiloride and ouabain were used as inhibitors of cellular transportation via ion transporters. Control values R™ were low in lower lobe visceral, caudal costal parietal and diaphragmatic pleura. Amiloride increased R™ at all locations except upper visceral and mediastinum. Higher R™ increases were found in caudal parietal and dorsal diaphragmatic samples. Ouabain increased R™ of lower visceral, caudal parietal and diaphragmatic pleura but not of mediastinal specimens. Observations made in sheep tissue were comparable with human visceral, parietal and mediastinal regions. In conclusion, results suggest heterogeneity of trans-mesothelial permeability among different pleural locations in sheep as was the case for humans. Thoracic surgeons should consider physiology function of each part of pleural cavity before pleural tissue manipulation. Observations made in sheep may be used to understand human physiology

Role of Histamine in Altering Fluid Recycling in Normal and Post-Traumatic Rabbit Peritoneum

This study aims to investigate if histamine induces electrochemical alterations in the normal and post-traumatic peritoneum. Peritoneal rabbit specimens were obtained before surgery and 10 days post-operatively and were mounted in Ussing chambers. Histamine solutions were added facing the intra-peritoneal and outer-peritoneal surface. Dimetindene maleate-, cetirizine-, and ranitidine-pretreated specimens were used to investigate histamine receptor involvement, whereas amiloride- and ouabain-pretreated specimens were used to investigate ion transportation blockage involvement. Trans-mesothelial resistance (R (TM) ) was determined. Histamine-increased R (TM) intra-peritoneally and decreased it outer-peritoneally. A less intense effect was induced in post-traumatic specimens. Dimetindene maleate, cetirizine, amiloride, and ouabain totally inhibited this effect, whereas ranitidine only had a partial effect. Histamine induces electrochemical alterations in the normal and post-operative peritoneum. This effect is mediated by interaction with histamine receptors, hindering the normal process of ion trans-mesothelial transportation