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KMID : 0362919940120010017
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Journal of the Korean Society for Therapeutic Radiology and Oncology
1994 Volume.12 No. 1 p.17 ~ p.25
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Role of Blood Flow vs. O₂Consumption in Nicotinamide-induced Increase pO₂in a Murine Tumor
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Lee In-Tae
Cho Moon-June
Demhartner Thomas J.
Gerweck Leo E.
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Abstract
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We evaluated the effect of nicotinamide on cellular O₂consumption and metabolic status i.e., adenylate phosphates and NAD+ in-vitro, and changes in blood flow in-vivo, to determine whether changes in cellular metabolism or increased oxygen availability, was responsible for increased tumor oxygenation. Thirty min. Pre-incubation of cells with~4mM (=500mg/kg) nicotinamide resulted in no change in cellular O₂consumption. Similarly, neither the adenylate phosphates nor the cellular NAD+ levels were altered in the presence of~4mM nicotinamide. In-vivo, nicotinamide (500mg/kg) increased O₂availability as estimated by changes in relative tumor blood flow (RBC flux). The changes in RBC flux measured by the laser Doppler method, were tumor volume dependent and increased from~35% in~150mm³tumors to~75% in~500mm³tumors. In conclusion, these observations indicate a reduction in local tissue O₂consumption is not a mechanism of improved tumor oxygenation by nicotinamide in FsaⅡ murine tumor model. The primary mechanism of increased pO₂appears to be an increased local tumor blood flow.
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KEYWORD
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Nicotinamide, Oxygen consumption (Qo2 ), Tumor blood flow (TBF) Laser Doppler flowmetry
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