μ-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.