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Integral-mass balance method for determination of solvent drag reflection coefficient
Abstract:
We have developed the integral-mass balance (IMB) method to measure the solvent drag reflection coefficient (sigma f) for transcapillary macromolecular transport in skeletal muscle and other organs. Of course, sigma f is calculated from the cumulative amounts of water and macromolecule that move convectively across the microvascular membrane as determined from changes in hematocrit and plasma macromolecule concentration over a period of fluid filtration. We have investigated the effects of both theoretical and experimental factors that affect the validity and accuracy of the method. The effect of the following factors on sigma f determination by the IMB method were explored: low Peclet number; random-measurement errors; and systematic errors due to vascular leakage, hemolysis of red blood cells, evaporation, and osmolality changes. We found that all of these factors produced overestimations of sigma f, but their effects could be corrected. Also, appropriate experimental design could minimize these effects. Experiments using the IMB method in the isolated, perfused cat hindlimb preparation to determine sigma f for albumin and plasma proteins resulted in mean values of 0.82 +/- 0.08 (SD) (n = 7) and 0.83 +/- 0.02 (n = 4), respectively.
Insights
The integral-mass balance (IMB) method accurately measures the solvent drag reflection coefficient (sigma f) for macromolecular transport. This method corrects for errors, ensuring reliable data for microvascular studies.
Area of Science:
- Physiology
- Biophysics
- Biomedical Engineering
Background:
- Transcapillary macromolecular transport is crucial for organ function.
- Accurate measurement of the solvent drag reflection coefficient (sigma f) is essential for understanding this process.
- Existing methods may be limited in accuracy and scope.
Purpose of the Study:
- To introduce and validate the integral-mass balance (IMB) method for measuring sigma f.
- To assess the impact of theoretical and experimental factors on IMB method accuracy.
- To determine sigma f for albumin and plasma proteins in skeletal muscle.
Main Methods:
- Developed the integral-mass balance (IMB) method using cumulative water and macromolecule movement.
- Analyzed effects of low Peclet number, measurement errors, and systematic errors (leakage, hemolysis, evaporation, osmolality).
- Validated the IMB method in an isolated, perfused cat hindlimb preparation.
Main Results:
- The IMB method accurately quantifies sigma f for transcapillary macromolecular transport.
- Identified and quantified overestimations of sigma f caused by various error sources.
- Demonstrated that these errors can be corrected and minimized through experimental design.
- Obtained mean sigma f values of 0.82 +/- 0.08 for albumin and 0.83 +/- 0.02 for plasma proteins.
Conclusions:
- The integral-mass balance (IMB) method provides a valid and accurate approach to measure the solvent drag reflection coefficient (sigma f).
- The method is robust against common experimental errors, which can be corrected.
- Results support the IMB method's utility in studying macromolecular transport in various organs.