Hydrostatic and osmotic pressures modulate partitioning of tissue water in abdominal muscle during dialysis

El Rasheid Zakaria, Joanne Lofthouse, Michael F. Flessner

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Objectives: To investigate the effect of simultaneous exposure of anterior abdominal muscle (AAM) to changes in intraperitoneal hydrostatic pressure (P(i)p)) and to osmolality of peritoneal fluid on total tissue water (TTW) and on the pattern of distribution of TTW in the AAM. Design: A pilot study of single 60-min dwells in anesthetized Sprague-Dawley (SD) rats, dialyzed with either isotonic (290 mOsm/kg) or hypertonic (510 mOsm/kg) dialysis solutions at nominal P(ip) of 0 mmHg or 6 mmHg. Measurements: TTW (from dry-weight-to-wet-weight ratios) can be divided into the extracellular volume [θ(ec), from quantitative autoradiography (QAR) with 14C-mannitol] and intracellular volume (θ(ic) = TTW - θ(ec)). θ(ec) = θ(if) + θ(iv), where θ(if) = interstitial volume and θ(iv) = vascular volume [from QAR with 131I-immunoglobulin G (IgG)]. All measured parameters are standardized to tissue dry weight and expressed as mean ± standard error. Results: Regardless of the osmolality of the dialysis solution, elevation of P(ip) to 6 mmHg results in tissue expansion, primarily in θ(if), which is doubled to 1.71 ± 0.11 mL/g dry weight and 1.60 ± 0.17 mL/g dry weight with isotonic and hypertonic dialysis, respectively, as compared to controls (0.64 ± 0.04 mL/g dry weight). The local θ(iv) was not affected by P(ip) or osmolality of the bathing solution. The overall θ(iv) is 0.046 ± 0.006 mL/g dry weight. A two-way analysis of variance (ANOVA) to access the effect of osmolality and P(ip) on θ(ic) demonstrated no significant change in θ(ic) (F = 1.2, p > 0.1) as calculated for controls (3.13 ± 0.19 mL/g dry weight), after isotonic dialysis (3.13 ± 0.20 mL/g dry weight), or after hypertonic dialysis (2.77 ± 0.30 mL/g dry weight). Conclusion: Elevation of P(ip) to 6 mmHg significantly increased TTW and expanded the tissue. Tissue expansion is primarily in interstitium (θ(if)), which is doubled from control value regardless of dialysis fluid osmolality.

Original languageEnglish (US)
Pages (from-to)S208-S211
JournalPeritoneal Dialysis International
Issue numberSUPPL. 2
StatePublished - 1999
Externally publishedYes


  • Convection
  • Interstitium
  • Intraperitoneal pressure

ASJC Scopus subject areas

  • Nephrology


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