Transdiaphragmatic transport of tracer albumin from peritoneal to pleural liquid measured in rats.
In conscious Wistar-Kyoto rats, we studied the uptake of radioactive tracer (125)I-albumin into the pleural space and circulation after intraperitoneal (IP) injections with 1 or 5 ml of Ringer solution (3 g/dl albumin). Postmortem, we sampled pleural liquid, peritoneal liquid, and blood plasma 2-48 h after IP injection and measured their radioactivity and protein concentration. Tracer concentration was greater in pleural liquid than in plasma approximately 3 h after injection with both IP injection volumes. This behavior indicated transport of tracer through the diaphragm into the pleural space. A dynamic analysis of the tracer uptake with 5-ml IP injections showed that at least 50% of the total pleural flow was via the diaphragm. A similar estimate was derived from an analysis of total protein concentrations. Both estimates were based on restricted pleural capillary filtration and unrestricted transdiaphragmatic transport. The 5-ml IP injections did not change plasma protein concentration but increased pleural and peritoneal protein concentrations from control values by 22 and 30%, respectively. These changes were consistent with a small (approximately 8%) increase in capillary filtration and a small (approximately 20%) reduction in transdiaphragmatic flow from control values, consistent with the small (3%) decrease in hydration measured in diaphragm muscle. Thus the pleural uptake of tracer via the diaphragm with the IP injections occurred by the near-normal transport of liquid and protein.
Lai-Fook
Stephen J
SJ
Center for Biomedical Engineering, University of Kentucky, Lexington, KY 40506-0070, USA. laifook@uky.edu
Houtz
Pamela K
PK
Jones
Philip D
PD
D000418:Albumins / Q000493:pharmacokinetics*; D000818:Animals; D001202:Ascitic Fluid / Q000378:metabolism*; D001693:Biological Transport, Active; D002199:Capillary Permeability; D003964:Diaphragm / Q000378:metabolism*; D008833:Microcirculation / Q000378:metabolism*; D035422:Pleural Cavity / Q000378:metabolism*; D010996:Pleural Effusion / Q000378:metabolism*; D051381:Rats; D011921:Rats, Inbred WKY
D000418:Albumins