Interstitial fluid pressure and hemodynamics in a sarcoma implanted in the rat tail

Area of Science:

• Oncology
• Physiology
• Biomedical Engineering

Background:

• Tumor blood flow is crucial for growth and treatment response.
• Interstitial fluid pressure (IFP) is elevated in tumors and may affect perfusion.
• Understanding IFP's role is key to improving cancer therapies.

Purpose of the Study:

• To investigate how changes in interstitial fluid pressure (IFP) and perfusion pressure influence tumor blood flow.
• To compare the effect of IFP on tumor perfusion versus normal tissue perfusion.

Main Methods:

• Sarcoma tumors were implanted in Lister rats.
• Hydrogen gas washout technique measured blood flow in tumors and tail skin.
• Wick-in-needle technique measured interstitial fluid pressure (IFP).
• IFP was manipulated by tail cuff inflation and plasma volume expansion.

Main Results:

• Control tumor blood flow (0.18 ml/min·g) was similar to tail skin.
• Elevated IFP (37.6 mm Hg) due to tail cuff inflation reduced tumor and tail skin blood flow by 45-70%.
• Further IFP elevation (50.5 mm Hg) in plasma-expanded rats reduced blood flow by 40-56%.
• Tumor blood flow was unaffected by a 25 mm Hg reduction in tail arterial pressure.

Conclusions:

• High interstitial fluid pressure (IFP) does not disproportionately affect tumor perfusion compared to normal host tissue.
• Tumor perfusion pressure appears to be regulated similarly in tumors and normal tissues under varying IFP conditions.