Oxidative stress causes a protein kinase C-independent increase of paracellular permeability in an in vitro epithelial model.

To evaluate the response of an epithelial barrier to a moderate but sustained oxidative stress, we cultured monolayers of Madin Darby canine kidney cells on microporous filters and exposed them to the hypoxanthine-xanthine oxidase (HX-XO) reaction. The transepithelial permeability coefficient for mannitol (Pm) was assessed as a marker of paracellular permeability. When the oxidative stress was limited in intensity and duration (production of 10 nmol/ml/min O2- with generation of 467 +/- 30 nmol/ml H2O2 over 1 h), we observed an increase of Pm with a delay of several hours (324 +/- 65% of baseline by 6 h, P < 0.005). There was complete return to control values by 24 h. The increase of Pm did not appear to be related to a depletion of cellular ATP. Protein kinase C (PKC) activity did not increase, and the rise in Pm was not prevented by CGP 41,251, a specific inhibitor of PKC. By contrast, CGP 41,251 inhibited the Pm increase that was elicited by PDBU, a phorbol ester that activates PKC. In our model, we conclude that a reversible increase of paracellular permeability occurs after oxidative stress independently of ATP depletion or PKC activation. Other, as yet unknown mechanisms have to be involved in this process.

Upper respiratory tract secretions: pathophysiology.

Nasal fluid is a heterogeneous substance. It consists largely of a secretory product derived from the 100,000 small seromucous glands. The anterior part of the nose has a relatively high secretory capacity, but this does not seem to be caused by secretion from the 200 anterior serous glands. Compared to sputum, nasal secretion has a lower viscosity, but comparable spinability; it has a lower dry weight, and content of sulphate, sugars and most proteins, but a comparable level of albumin. Watery rhinorrhoea is mainly reflex-mediated. Watery, but not purulent nasal discharge can be reduced by the cholinoceptor antagonist, ipratropium, administered in a dose which matches the degree of the symptoms. It seems likely that the nose, in some respects, can serve as a model for the analysis of airway secretions, but a comparative study of nasal and of bronchial secretions sampled in an identical way is warranted.

Quantitative features of goblet cells in the rat tracheobronchial tree.

The whole-mount quantitative method was used to study the density and distribution of goblet cells in the male rat lung. The airway of the left lung in 10 lung specimens were dissected downwards in the axial pathway and the airway generation levels were determined by an exact numbering system. The entire bronchial mucous membrane was separated and stained according to the PAS-alcian blue whole-mount method. There was a significant decrease in goblet cell density from the proximal to the distal airways (6 to 0 cells/field). The overall median density was 1 cell/field, corresponding to 56 cells per mm2. The goblet cells were irregularly distributed throughout the airways. When using the rat airway epithelium as an animal model system the whole-mount method is recommended and this study provides an exact quantitative mapping of the rat airway epithelial system to be used for baseline comparison.

Quantitative study of goblet cells in the upper lobe of the normal human lung.

Goblet-cell density and distribution were studied in ten specimens of the human adult lung. The bronchial tree of the left upper lobe was dissected, and the bronchial mucosa separated and stained by the whole-mount periodic acid-Schiffalcian blue method. There was a significant fall in the goblet-cell density from the proximal to the distal airways. In the upper division, the number decreased from 144 cells per field (second generation) to 80 cells per field (14th generation), and in the lingular division it decreased from 137 (fourth generation) to 77 cell (18th generation). The overall goblet-cell density for the upper lobe was 113 cells per field, corresponding to 6,400 cells per square millimeter. No particular pattern in cell distribution was noticed; the cells were irregularly distributed all along the bronchial tree without any well-defined distribution pattern. In the ten lung specimens studied, goblet-cell density did not correlate with smoking habit, sex, or age.

Goblet-cell density in the human lung--whole-mount study of the normal left lower lobe.

The whole-mount quantitative method was used to study goblet-cell density and distribution in the adult human lung. The airways of the lower lobe in 10 lung specimens were dissected downwards in the axial pathway and airway generation levels were determined by an exact numbering system. The entire bronchial mucous membrane was separated from the underlying structures and stained with the PAS-alcian blue whole-mount method. 11 generations (3-13) were studied in all 10 specimens. Goblet cells were irregularly distributed throughout the airways. There was a highly significant decrease in goblet-cell density from proximal to distal airways (145 to 92 cells/field). The overall median density was 123 cells per field, which corresponds to 6,950 cells per square mm. There was no obvious difference between the cases as related to smoking habits, sex and age.