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Effect of convection on diffusion of small solutes through tissue
Author(s) -
Flessner Michael F,
Credit Kimberly,
Henderson Karla,
Li Xiarong
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a488-c
Subject(s) - tonicity , isotonic , mannitol , peritoneum , chemistry , peritoneal cavity , diffusion , convection , biophysics , anatomy , thermodynamics , medicine , biochemistry , biology , physics
Transport of small solutes (MW< 500 da) through tissue is typically diffusion‐dominated. In the special case of intraperitoneal therapy, hypertonic solutions are used to introduce drugs or nutrients into the body. The hyperosmolar solution induces convection from the body into the cavity, opposing solute delivery. Our hypothesis is that this convection will retard small solute transfer into peritoneal tissue, if its magnitude approaches the solute mass transfer coefficient (MTC). To test this, we measured the effect of osmotic volume flux (Flux osm ) on the mannitol MTC using plastic chambers affixed to the abdominal wall peritoneum of 12 SD rats. The chamber fixes the fluid contact area of the peritoneum and permits determination of volume and concentration versus time and the calculation of MTC. 14 C‐mannitol transport from the chamber to the tissue was measured during two 90 min periods of testing under isotonic or hypertonic (~500 mosm/kg) conditions. If convection from the tissue to the chamber had a significant effect, the magnitude of MTC would decrease. Our results for the isotonic case resulted in a mean ± SE (cm/min × 10 3 ) of: Flux osm , −0.053 ± 0.027 and MTC of 3.09 ± 0.40. The hypertonic case demonstrated a markedly positive Flux osm into the chamber of 2.33 ± 0.33 (p<0.05 vs isotonic) but no significant change in the MTC (2.80 ± 0.35), disproving our hypothesis. We conclude that this level of convection has insignificant effects on the diffusive transfer of small solutes across the peritoneum into the underlying tissue.