Insulin-induced electrochemical changes in pleura are associated with the location within the pleural cavity.

AIM: We investigated the effects of insulin on the electrophysiology of sheep pleural specimens obtained from the upper and lower parts of the pleural cavity and the insulin receptor abundance in these regions. MATERIALS AND METHODS: Sheep pleural specimens were obtained from the upper and lower lung lobes and from the 1st-4th and 8th-12th ribs and were mounted between Ussing chambers. Insulin 10(-7) M was added on the mesothelial surface with Insulin Receptor (IR) inhibitor in some experiments. Trans-mesothelial Resistance (R(™)) was determined. Immunohistochemistry for the presence of IR differences was performed. RESULTS: Insulin increased the R(™) of all pleural regions. Higher R(™) increase was demonstrated in lower lobe visceral and in caudal parietal specimens. The R(™) increase demonstrated in caudal parietal had the tendency to be higher than that observed in the lower lobe visceral specimens. IR inhibitor abolished insulin's effect in all regions. Immunostaining was more intense for parietal and for caudal parietal specimens when compared with the visceral and lower lobe visceral specimens. CONCLUSION: Insulin induces electrochemical alterations that vary depending on the location of specimens within the pleural cavity which possibly is not correlated with insulin receptors variations.

Effect of histamine on the electrophysiology of the human parietal pleura.

INTRODUCTION: Histamine is involved in the pathogenesis of numerous diseases and regulates the permeability of different tissues. The aim of this study is to investigate the effects of histamine on the electrophysiology of human parietal pleura and the underlying mechanisms involved. MATERIALS AND METHODS: Pleural specimens were obtained from patients subjected to thoracic surgery and were mounted in Ussing chambers. Histamine solutions (1µM to 1mM) were applied in native and pretreated specimens with dimetindene maleate, cetirizine, ranitidine, amiloride and ouabain. Trans-mesothelial resistance was determined (R(TM)). RESULTS: Histamine induced a rapid R(TM) increase on the mesothelial (p = 0.008) and a decrease on the interstitial surface (p = 0.029). This effect was dose-dependent and was totally abolished by dimetindene maleate, cetirizine and amiloride and partially by ranitidine and ouabain. CONCLUSIONS: Histamine induces acute electrochemical changes in human pleura mainly via interaction with the H(1) and partially with the H(2) histamine receptors. It also interferes with trans-cellular permeability and therefore may participate in pleural fluid recycling.

Permeability alterations after surgical trauma in normal rabbit peritoneum.

BACKGROUND: To investigate whether surgical trauma in a rabbit adhesion formation model and the administration of normal saline (N/S), icodextrin (ID) and/or dimetindene maleate (DM) changes the permeability of the normal rabbit parietal peritoneum. MATERIALS AND METHODS: A total of 45 female rabbits were operated on for adhesion formation and were euthanized 10 days later. In some rabbits, ID or N/S was instilled intraabdominally during operation, whereas in others DM was infused intravenously. In others, ID plus DM or no agent was used. Specimens were obtained postoperatively and were mounted between Ussing chambers. Amiloride was used to investigate Na(+) channels. Transmesothelial resistance (R(TM)) was determined as a permeability indicator. RESULTS: Amiloride increased the R(TM) of both surfaces. Surgical trauma increased R(TM) and partially inhibited the effect of amiloride. ID and N/S increased R(TM) and inhibited the effect of amiloride. Use of DM did not change R(TM) and did not inhibit the effect of amiloride. Use of ID plus DM slightly increased R(TM), but the effect of amiloride was blocked. CONCLUSIONS: Surgical trauma impairs the permeability of the normal rabbit parietal peritoneum. ID or N/S surmounted this effect, but DM did not, suggesting that surgical trauma is a diffuse process. Antiadhesion measures influence peritoneal physiology.

Insulin-induced electrophysiology changes in human pleura are mediated via its receptor.

BACKGROUND: Insulin directly changes the sheep pleural electrophysiology. The aim of this study was to investigate whether insulin induces similar effects in human pleura, to clarify insulin receptor's involvement, and to demonstrate if glibenclamide (hypoglycemic agent) reverses this effect. METHODS: Human parietal pleural specimens were mounted in Ussing chambers. Solutions containing insulin or glibenclamide and insulin with anti-insulin antibody, anti-insulin receptor antibody, and glibenclamide were used. The transmesothelial resistance (R(TM)) was determined. Immunohistochemistry for the presence of Insulin Receptors (IRa, IRb) was also performed. RESULTS: Insulin increased R(TM) within 1st min (P = .016), when added mesothelially which was inhibited by the anti-insulin and anti-insulin receptor antibodies. Glibenclamide also eliminated the insulin-induced changes. Immunohistochemistry verified the presence of IRa and IRb. CONCLUSION: Insulin induces electrochemical changes in humans as in sheep via interaction with its receptor. This effect is abolished by glibenclamide.

Role of electrolytes and glucose in the insulin-induced electrochemical effect in sheep pleura.

AIM: Insulin induces electrochemical alterations in sheep visceral and parietal pleura, an effect abolished by the Na (+)-channel blocker amiloride and the Na (+)-K (+) pump inhibitor ouabain. The aim of this study was to further investigate the role of different electrolytes and glucose in these electrochemical changes. MATERIALS AND METHODS: Sheep pleural specimens were mounted in Ussing chambers. Insulin (10 (-7)M) was added mesothelially in Na (+), K (+), Ca (2+)-free, low H (+) and glucose solutions. In other experiments, specimens were pretreated with K (+) and Ca (2+)-free Krebs solutions. Trans-mesothelial Resistance was determined. RESULTS: Insulin did not increase Trans-mesothelial Resistance of visceral and parietal pleura in K (+)-free (p=0.008 and p=0.028 respectively), Ca (2+)-free (p=0.006 and p=0.012 respectively) and low glucose (p=0.009 and p=0.03 respectively) solutions. This effect was totally inhibited in Na (+)-free solutions or in specimens pretreated with Ca (2+) -free Krebs solution and partially inhibited, when low H (+) solutions were used (p=0.042 for visceral and p=0.045 for parietal). CONCLUSION: Insulin-induced electrochemical changes in sheep pleura are mainly associated with alterations in Na (+) and Ca (2+) concentrations. Since amiloride and ouabain abolish these electrochemical changes, it may be suggested that insulin could influence the pleural fluid recycling, mainly via the Na (+) transportation system, irrespective of the glucose content.

Insulin alters the permeability of sheep pleura.

AIM: Insulin promotes ion transportation across epithelia, mainly kidneys, leading to water and electrolyte abnormalities, possibly causing 'insulin oedema syndrome', which rarely presents as pleural effusion. Direct stimulation of sheep pleura by insulin and the possible electrophysiology mechanisms involved were investigated. MATERIAL AND METHODS: Sheep visceral and parietal pleural specimens were mounted between Ussing chambers. Insulin solutions (10 (-9) to 10 (-5) M), L-NAME, Nitroprussid sodium, amiloride and ouabain were used. Trans-mesothelial Resistance was determined. Immunohistochemistry for presence of Insulin Receptors was performed. RESULTS: Insulin increased Trans-mesothelial Resistance within 1st minute when added mesothelially of visceral (p=0.008) and parietal pleura (p=0.046) for concentrations higher than 10 (-7) M. L-NAME or Nitroprussid sodium didn't but amiloride and ouabain inhibited insulin's effect. Immunohistochemistry revealed the presence of Insulin Receptors. CONCLUSION: Insulin changes the permeability of sheep pleura by altering its electrophysiology and may interfere in pleural effusion formation. Involvement of Insulin Receptors may be suggested.

Low glucose level and low pH alter the electrochemical function of human parietal pleura.

The aim of the present study was to investigate whether low glucose and pH level, which are usually measured in complicated pleural effusions, alter the electrochemical function of healthy human parietal pleura. Parietal pleural pieces were stripped from 66 patients during thoracic surgery and were mounted in Ussing chambers. Krebs' solutions containing different glucose levels (0, 40 and 100 mg) and balanced at different pH levels (7.4, 7.3 and 7.2) were added to the pleural cavity surface of the pieces. Transmesothelial potential difference was measured at various time-points as an electrophysiological variable and transmesothelial resistance (R(TM)) was calculated using Ohm's law. When normal-glucose Krebs at pH 7.45 was used, R(TM) remained unchanged over time, but when low-glucose Krebs was used, R(TM) decreased. Krebs without glucose caused the greatest decrease in R(TM). Use of low-pH Krebs decreased R(TM). The lower the pH of the Krebs, the faster the decrease in R(TM) and the greater the effect. The decrease in R(TM) was greater with low-pH than with low-glucose Krebs. Low glucose and low pH caused an additive decrease in R(TM). Low glucose concentration and low pH cause alteration of the electrochemical function of human parietal pleura and could act as agents that lead to further exudate progression.