The effect of opioids on the electrical resistance of sheep's pleura and pericardium

The effect of morphine on the transmesothelial resistance (RTM) of sheep’s visceral and parietal pleura and parietal pericardium was studied using the Ussing chamber technique. The basal values were found to be 19,41 ± 0.31 Ω×cm2, 19,57 ± 0.32 Ω×cm2 and 21 ± 0.61 Ω×cm2, respectively. Immediately after the addition of morphine (10-9M) both apically and basolaterally on the parietal pleura and the parietal pericardium, these values were significantly increased (P<0.05). The addition of morphine (10-9M) on the visceral pleura caused a statistically significant increase of the RTM, only when added basolaterally. Addition of the nonselective opioid receptor blocker, naloxone (10-5M), suppressed this effect at all sites. The addition of loperamide (10-9Μ) as a μ opioid receptor agonist, on the same sites as morphine, caused a statistically significant increase of the RTM only when was added basolaterally on the visceral pleura. The addition of loperamide (10-6Μ) as a voltage dependent Ca2+ channels – L type blocker, suppressed the morphine effect on the basal surface of all three tissues. The addition of ouabain (10-3Μ), individually or combinationally with morphine, caused an additive increase of the RTM at all sites where morphine was effective. In conclusion, our results show that morphine has a rapid effect on the three tissues, with differences regarding to the surface and the duration of the effect. The rapid effect is mediated by the stimulation of the μ opioid receptors at all sites. The effect of morphine on the basal surface of both the pleurae and the parietal pericardium appears to be mediated by the voltage dependent Ca2+ channels – L type. The stimulation of μ opioid receptors never appears to be related with the Na+/K+ ATPase. The differences regarding the sites of activity between morphine and loperamide, probably signify the existence of multiple subtypes of μ opioid receptors. Contrary to the other sites, the effect of morphine on the basal surface of both the visceral pleura and the parietal pericardium was prolonged. This difference is probably related with same differences regarding the number or the distribution of the μ opioid receptors subtypes.Μελετήθηκε η επίδραση της μορφίνης στη διαμεσοθηλιακή αντίσταση (RTM) του τοιχωματικού και περισπλάχνιου υπεζωκότα και του τοιχωματικού περικαρδίου προβάτου, χρησιμοποιώντας την τεχνική Ussing Chamber. Η τιμές αναφοράς της RTM για τους παραπάνω ιστούς ήταν 19,57 ± 0.32 Ω×cm2, 19,41 ± 0.31 Ω×cm2 και 21 ± 0.61 Ω×cm2, αντίστοιχα. Ταχέως μετά την εφαρμογή μορφίνης (10-9M) στην κορυφαία και βασική επιφάνεια του τοιχωματικού υπεζωκότα και του τοιχωματικού περικαρδίου, αυτές οι τιμές αυξήθηκαν στατιστικά σημαντικά (P<0.05). Η εφαρμογή της μορφίνης στον περισπλάχνιο υπεζωκότα, προκάλεσε στατιστικά σημαντική αύξηση της RTM μόνο στη βασική επιφάνεια. Προσθήκη του μη ειδικού αναστολέα των υποδοχέων των οπιοειδών ναλοξόνη (10-5M), κατέστειλε τη δράση της μορφίνης σε όλες τις θέσεις που ήταν στατιστικά σημαντική. Η εφαρμογή της λοπεραμίδης (10-9Μ), ως αγωνιστή των μ υποδοχέων των οπιοειδών, στις ίδιες θέσεις με τη μορφίνη προκάλεσε στατιστικά σημαντική αύξηση της RTM μόνο στη βασική επιφάνεια του περισπλάχνιου υπεζωκότα. Η χρήση της λοπεραμίδης ως αναστολέα των εξαρτώμενων από το δυναμικό διαύλων Ca2+ τύπου L (10-6M), κατέστειλε τη δράση της μορφίνης μόνο στις βασικές επιφάνειες και των τριών ιστών. Η εφαρμογή ουαμπαΐνης (10-3Μ), μεμονωμένα και σε συνδυασμό με τη μορφίνη, έδειξε αθροιστική αύξηση της RTM σε όλες τις θέσεις δράσης της μορφίνης. Συμπερασματικά, η μορφίνη φαίνεται να έχει ταχεία επίδραση και στους τρεις ιστούς αλλά με διαφορές ως προς την επιφάνεια και τη διάρκεια δράσης. Αυτή η ταχεία επίδραση μεσολαβείται από τη διέγερση των μ υποδοχέων των οπιοειδών σε όλες τις θέσεις. Στις βασικές επιφάνειες του τοιχωματικού και περισπλάχνιου υπεζωκότα και του τοιχωματικού περικαρδίου, η διέγερση των μ υποδοχέων φαίνεται να σχετίζεται με τους εξαρτώμενους από το δυναμικό διαύλων Ca2+ τύπου L. Σε καμία από τις θέσεις δράσης της μορφίνης, η διέγερση των μ υποδοχέων δε φαίνεται να σχετίζεται τη Na+/K+ ATPαση. Η διαφορές μεταξύ μορφίνης και λοπεραμίδης ως προς τις θέσεις δράσης, υποδηλώνει την έκφραση διαφόρων υποτύπων μ υποδοχέων των οπιοειδών. Στη βασική επιφάνεια του περισπλάχνιου υπεζωκότα και του τοιχωματικού περικαρδίου, η δράση της μορφίνης ήταν παρατεταμένη, ενώ στις υπόλοιπες θέσεις ήταν βραχυχρόνια. Η διαφορά αυτή πιθανόν να σχετίζεται με διαφορές ως προς τον αριθμό ή την κατανομή των υποτύπων των μ υποδοχέων των οπιοειδών

mu-Opioid influence on transmesothelial resistance of isolated sheep pleura and parietal pericardium

The effect of morphine (mu-opioid receptor agonist) on the transmesotbelial resistance (R-TM) of sheep's pleura and parietal pericardium was studied using the Ussing chamber technique. Basal transmesothelial resistance of parietal pleura was found to be 19.57 +/- 0.32 Omega cm(2) and of visceral pleura was found to be 19.41 +/- 0.31 Omega cm(2), whereas that of parietal pericardium was found to be 22.83 +/- 10.4 Omega cm. Immediately after the addition of morphine (10(-9) M) both apically and basolaterally on the parietal pleura and parietal pericardium, these values were significantly increased (P < 0.05). On the contrary, addition of morphine (10(-9) M) resulted in a rapid increase, only when placed basolaterally on the visceral pleura (P < 0.05). In conclusion, our findings suggest that morphine, probably through pt-opioid stimulation, increases in vitro the transmesothelial resistance of the parietal pleura, of the visceral pleura when added basolaterally and of the parietal pericardium. (c) 2005 Elsevier B.V. All rights reserved

Effect of adrenaline on transmesothelial resistance of isolated sheep pleura

The effect of adrenaline on the transmesothelial resistance (R-TM) of sheep's visceral and parietal pleura was studied using the Ussing chamber technique. Basal transmesothelial resistance of visceral pleura was found to be 20.71 +/- 0.31 Omega cm(2), whereas that of parietal pleura was found to be 19.53 +/- 10.34 Omega cm(2). Immediately after the addition of adrenaline (10(-7) M) both apically and basolaterally on the visceral and parietal pleura, these values were significantly increased (P < 0.05). Addition of the nonselective beta-receptor blocker, propranolol (10(-5) M), suppressed this effect in both visceral and parietal pleura, while addition of the nonselective alpha-receptor blocker, phentolamine (10-5 M), partly suppressed the above-mentioned increase ill the parietal pleura. In conclusion. our results show that adrenaline has a rapid effect on both pleurae. This rapid effect is mediated by the stimulation of beta-adrenergic receptors in the case of visceral pleura, while in the case of parietal pleura this effect seems to be due to a stimulation of alpha- and beta-adrenergic receptors. On the visceral pleura the effect of adrenaline vanishes after some minutes and on the parietal this effect is more permanent than the visceral's one, suggesting differences in the distribution of the adrenergic receptors between the visceral and parietal pleura. (c) 2005 Elsevier B.V. All rights reserved

Physiology of pericardial fluid production and drainage

The pericardium is one of the serosal cavities of the mammals. It consists of two anatomical structures closely connected, an external sac of fibrous connective tissue, that is called fibrous pericardium and an internal that is called serous pericardium coating the internal surface of the fibrous pericardium (parietal layer) and the heart (visceral layer) forming the pericardial space. Between these two layers a small amount of fluid exists that is called pericardial fluid. The pericardial fluid is a product of ultrafiltration and is considered to be drained by lymphatic capillary bed mainly. Under normal conditions it provides lubrication during heart beating while the mesothelial cells that line the membrane may also have a role in the absorption of the pericardial fluid along with the pericardial lymphatics. Here, we provide a review of the the current literature regarding the physiology of the pericardial space and the regulation of pericardial fluid turnover and highlight the areas that need to be further investigated

Development of an egg-white bioassay for monitoring biotin levels in urine and serum

This article reports on the development of a simple and cost-effective bioassay for the detection of biotin in urine and serum, based on the very selective binding of avidin and biotin. Avidin was allowed to react without isolating it from egg white. Egg white was treated with the dye HABA, which binds to avidin. Upon subsequent treatment with biotin, HABA is released due to the high affinity of biotin to avidin. The amount of HABA released is proportional to the amount of biotin used

Effect of sodium-potassium pump inhibition by ouabain on the permeability of isolated visceral sheep peritoneum

The permeability for small solutes and the ultrafiltration capacity of the peritoneum are essential for effective peritoneal dialysis (PD) treatment. Elucidation of the factors that regulate these two properties is therefore of great importance. Ouabain, a potent inhibitor of the Na+-K+ pump has been shown to reduce fluid absorption in animal models of PD. In the present study, we used Ussing chamber experiments to investigate the effect of ouabain on the transmesothelial electrical resistance (RTM) of isolated visceral sheep peritoneum. Peritoneal samples from the omentum of adult sheep were isolated immediately after the deaths of the animals and were transferred to the laboratory in cooled Krebs-Ringer bicarbonate solution (4 degrees C, pH 7.5) bubbled with 95% O2/5% CO2. A planar sheet of visceral peritoneum was mounted in an Ussing-type chamber, and ouabain (10(-3) mol/L) was added apically and basolaterally. The RTM was measured before and serially for 30 minutes after the addition of ouabain. Because active ion transport is temperature-dependent, all measurements were taken at 37 degrees C. The results presented are the mean +/- standard error of 6 experiments. Before the addition of ouabain, the control RTM was measured as 21.26 +/- 0.57 Omega x cm2. Addition of ouabain basolaterally induced an increase in the RTM to 27.62 +/- 0.72 Omega x cm2 within 1 minute (p < 0.05), and this level persisted throughout the experiment. The effect of ouabain, when added apically, was similar, characterized by a rapid rise in the RTM to 24.66 +/- 0. 76 Omega x cm2 at 1 minute (p < 0. 05), with subsequent persistence at that level. A clear association between RTM and active ion transport has been shown in previous studies. The results of the present study, showing a rapid effect of ouabain on the RTM of visceral peritoneum, therefore clearly suggest that cell membrane Na+K+-ATPase is important for peritoneal ionic transport. In addition, ouabain was previously shown to reduce vasodilation and intraperitoneal sodium or to increase intraperitoneal volume, especially in the presence of conventional acidic solutions. Those findings, combined with the results of the present study, clearly indicate that intraperitoneal administration of digitalis glycosides may have some beneficial effect in PD patients; however the specific clinical implications need further investigation

mu-Opioid stimulation of isolated parietal sheep peritoneum decreases peritoneal permeability in vitro

The peritoneal mesothelium is one of the main barriers to ion transport in peritoneal dialysis. In a previous study, we showed the existence of a micro-opioid influence on the in vitro ionic permeability of serosal membranes (specifically, pleura and pericardium), which become less permeable to ionic currents after the action of morphine. In the present study, we used Ussing chamber experiments to investigate the effect of morphine on the transmesothelial electrical resistance (RTM) of isolated parietal sheep peritoneum. Peritoneal samples from the diaphragm of adult sheep were isolated directly after the death of the animals and were transferred to the laboratory within 30 minutes in a cooled Krebs-Ringer bicarbonate solution (4 degrees C, pH 7.5) bubbled with 95% O2/5% CO2. A planar sheet of parietal peritoneum was mounted in an Ussing-type chamber and morphine (10(-9) mol/L) was added apically and basolaterally. The RTM was measured before and serially for 30 minutes after the addition of morphine. Because active ion transport is temperature dependent, the Ussing chamber was held at 37 degrees C. Results presented are the mean +/- standard error of 6 experiments. The control RTM (before the addition of morphine) was 20.26 +/- 0.57 Omega x cm2. Addition of morphine basolaterally induced, within 1 minute, an increase in RTM of 24% +/- 4.8%, which declined thereafter (p < 0.01). When morphine was added apically, the results were not similar, because no significant change occurred in the RTM. The RTM is an established surrogate of peritoneal permeability. The results of the present study indicate rapid action of basolaterally added morphine on the permeability of the parietal peritoneum. The observed increase in the RTM indicates the existence in the parietal peritoneum of micro-opioid receptors that seem to prevail basolaterally. The clinical implications of these results should be further investigated

Endothelin-1 Acutely Reduces the Permeability of Visceral Sheep Peritoneum In Vitro Through Both Endothelin-A and Endothelin-B Receptors

Mesothelium is an important part of the peritoneal barrier for water and ion transport, essential for effective peritoneal dialysis (PD). Peritoneal fibrosis has been associated with PD treatment failure. Endothelin-1 (ET-1) is a potent vasoactive peptide, involved in pathologic fibrotic processes. Its action is mediated mainly by endothelin type A (ETA) and type B (ETB) receptors. The aim of this study was to investigate, by Ussing chamber experiments, the effect of ET-1 on the transmesothelial electrical resistance (RTM) of the isolated visceral sheep peritoneum. Intact sheets of visceral peritoneum were obtained from 40 adult sheep and mounted in Ussing-type chambers. ET-1 (107M), BQ-123 (ETA receptor antagonist; 106M), BQ-788 (ETB receptor antagonist; 106M), and their combinations were added on the apical and the basolateral side of the peritoneum. RTM was measured before and serially after addition of the substances, and changes were registered as percentage (RTM %). RTM increased within 1min after addition of ET-1 apically (RTM 65.03 +/- 15.87%; P<0.05) or basolaterally (RTM 85.5 +/- 20.86%; P<0.05). BQ-123 and BQ-788 and their combination significantly reduced (P<0.05) the effect of ET-1 to a similar degree in all cases. These results clearly indicate that ET-1 reduces ionic permeability of the visceral sheep peritoneum in vitro. Additionally, it is obvious that this inhibitory effect is mediated through both ETA and ETB receptors

The Alonissos Study: Cross-Sectional Study of the Community Respiratory Health Status in a Greek Healthcare Access Underprivileged Island

In this study, we investigated the self-reported (questionnaire-based) prevalence of Obstructive Sleep Apnoea Syndrome (OSAS) and the prevalence of Chronic Obstructive Pulmonary Diseases (COPD) in the context of demographics and adherence to the Mediterranean diet in the general population of Alonissos, a non-profit line island in Greece (i.e., with scarce boat transportation to the mainland). In this cross-sectional study, 236 inhabitants of Alonissos participated (circa 10% of the island’s population), and 115 males and 121 females were evaluated with appropriate questionnaires for OSAS, COPD, and adherence to the Mediterranean diet and subsequently underwent spirometry testing to establish COPD diagnosis. The self-reported prevalence of OSAS and COPD was 9.44% and 18.8%, respectively. However, only 8.99% of the participants were diagnosed with COPD based on their spirometry testing. Adherence to the Mediterranean Diet was moderate. The high prevalence of COPD and OSAS in this underprivileged island in terms of healthcare access highlights the need for improvements in health promotion and primary healthcare provision in non-profit line Greek islands. © 2022 by the authors

The Alonissos Study: Cross-Sectional Study of the Community Respiratory Health Status in a Greek Healthcare Access Underprivileged Island

In this study, we investigated the self-reported (questionnaire-based) prevalence of Obstructive Sleep Apnoea Syndrome (OSAS) and the prevalence of Chronic Obstructive Pulmonary Diseases (COPD) in the context of demographics and adherence to the Mediterranean diet in the general population of Alonissos, a non-profit line island in Greece (i.e., with scarce boat transportation to the mainland). In this cross-sectional study, 236 inhabitants of Alonissos participated (circa 10% of the island’s population), and 115 males and 121 females were evaluated with appropriate questionnaires for OSAS, COPD, and adherence to the Mediterranean diet and subsequently underwent spirometry testing to establish COPD diagnosis. The self-reported prevalence of OSAS and COPD was 9.44% and 18.8%, respectively. However, only 8.99% of the participants were diagnosed with COPD based on their spirometry testing. Adherence to the Mediterranean Diet was moderate. The high prevalence of COPD and OSAS in this underprivileged island in terms of healthcare access highlights the need for improvements in health promotion and primary healthcare provision in non-profit line Greek islands