4-acetamido-4--isothiocyanatostilbene-2-2--disulfonic-acid and Hydrothorax

Previous indirect findings have suggested the occurrence of solute-coupled liquid absorption from the pleural space, consistent with Na(+)-K(+)-ATPase on the interstitial side plus a Na(+)-H+ and CI(-)-HCO3- double exchange on the luminal side of the pleural mesothelium. To assess whether Na(+)-glucose cotransport also operates on the luminal side, the relationship between net rate of liquid absorption from the right pleural space (Jnet) and volume of liquid injected into this space (0.5, 1 or 2 ml) was determined in anaesthetized rabbits during hydrothoraces with phloridzin (10(-3)M) or with phloridzin plus 4-acetamido-4'-isothiocyanatostilbene-2, 2'-disulphonic acid (SITS; 1.5 x 10(-4)M). The relationship obtained during hydrothoraces with phloridzin was displaced downwards by 0.09 ml h-1 relative to that in control hydrothoraces (P < 0.01). The decrease in Jnet was similar in hydrothoraces of various sizes. The relationship obtained in hydrothoraces with phloridzin plus SITS was displaced downwards by 0.16 ml h-1 relative to that in control hydrothoraces (P < 0.01), i.e. the decrease in Jnet was similar to the sum (0.17 ml h-1) of the decreases in Jnet produced individually by phloridzin and by SITS (0.08 ml h-1). The decrease in Jnet was similar in hydrothoraces of differing size. The above findings are consistent with the occurrence of Na(+)-glucose cotransport on the luminal side of the pleural mesothelium, operating simultaneously with the double exchange also under physiological conditions.

Topics: 4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; Adsorption; Animals; Body Fluids; Hydrothorax; Phlorhizin; Pleura; Rabbits

The net rate of liquid flow and Na+ flux across the pleura was determined in anesthetised rabbit during hydrothoraces 0.5 to 5 ml in size, without and with amiloride. In the hydrothoraces with amiloride the net liquid flow and Na+ flux reversed when the volume injected approached zero. This indicates that the active Na+ transport and the consequent liquid absorption occur also under physiological conditions. The difference between the data obtained without and with amiloride provides the net solute-coupled liquid outflow and active Na+ efflux. These parameters increased linearly with the hydrothorax size up to 2 ml (0.39 ml/h and 54 muEq/h, respectively), and then levelled off. The linear relationship allowed their extrapolation to physiological conditions: 0.15 ml/h (0.07 ml.h-1.kg-1) and 21 muEq/h (0.1 muEq.h-1.cm-2). The increase in these parameters with the hydrothorax size seems due to the protein dilution caused by the Ringer injection, because it did not occur if Ringer was added with albumin to keep the protein concentration in the pleural liquid similar to that under physiological conditions.

Topics: 4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; Absorption; Albumins; Amiloride; Animals; Biological Transport, Active; Hydrothorax; Pleura; Pleural Effusion; Proteins; Pulmonary Ventilation; Rabbits; Sodium; Tidal Volume