Effect of flow on hydraulic conductivity and reflection coefficient of rabbit mesentery.
OBJECTIVE
To measure the hydraulic conductivity and reflection coefficient for albumin, as defined by the Starling equation, in rabbit mesentery.


METHODS
A section of rabbit mesentery was fixed between two chambers filled with lactated Ringer solution. Flow (Q) of Ringer solution was measured across the mesentery at driving pressures (delta P) between 1 and 6 cm H2O. Hydraulic conductivity was proportional to the slope of the Q-delta P curve. At constant delta P (approximately -2, -4, or -6 cm H2O), flow was measured at three different albumin concentration differences (0.5, 1, and 1.5 g/dl). Unstirred layer effects were minimized by magnetic stirrers. Reflection coefficient was the negative of the slope of the Q-delta pi curve divided by the slope of the Q-delta P curve, where delta pi was the albumin osmotic pressure difference. Hydraulic conductivity was measured before and after testicular hyaluronidase was added to the Ringer solution.


RESULTS
There was no significant difference in conductivity per unit area (Lp) for the three different driving pressures. Hyaluronidase increased hydraulic conductivity significantly (p < 0.01) by 72 +/- 56%, indicating that hyaluronan and other glycosaminoglycans contributed to tissue fluid resistance. Reflection coefficient (sigma) increased from 0.02 to 0.14 as flow increased eightfold.


CONCLUSIONS
The results suggest that the mesentery tissue provides little restriction to the passage of albumin. The increase in conductivity in the presence of hyaluronidase indicates that tissue hyaluronan and other glycosaminoglycans provide fluid resistance to bulk flow.
Parameswaran
S
S
Center for Biomedical Engineering, University of Kentucky, Lexington 40506-0070, USA.
Brown
L V
LV
Lai-Fook
S J
SJ
D000418:Albumins / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D004058:Diffusion; D004730:Endothelium, Vascular / Q000378:metabolism; D006025:Glycosaminoglycans / Q000737:chemistry; D006820:Hyaluronic Acid / Q000737:chemistry; D006821:Hyaluronoglucosaminidase / Q000494:pharmacology; D007552:Isotonic Solutions / Q000378:metabolism; D008643:Mesentery / Q000098:blood supply / Q000187:drug effects / Q000502:physiology*; D008833:Microcirculation; D009997:Osmotic Pressure; D010539:Permeability; D011817:Rabbits; D012212:Rheology; D000077325:Ringer's Lactate
D000418:Albumins; D006025:Glycosaminoglycans; D007552:Isotonic Solutions; D000077325:Ringer's Lactate; D006820:Hyaluronic Acid; D006821:Hyaluronoglucosaminidase