Hyperglycemia (
blood glucose, > 20 mmol/liter) caused a 90 to 100% inhibition of blood flow in the solid
Yoshida sarcoma of rat feet, as measured by the fractional distribution of 86Rb and 133Xe clearance. Blood flow through the normal gastrocnemius muscle was increased by 50%, while liver blood flow remained unaltered.
Hyperglycemia abrogated the temperature differential (approximately 1 degree) between the heating bath and the
tumor, promoting more uniform
tumor heating. During the period of reduced blood flow, the pH of the
tumor extracellular fluid, measured by miniature glass
electrode, declined from 7.19 to 6.63 due to decreased efflux of
lactate from the
tumor.
Tumor intracellular pH, measured by partitioning of
dimethyloxazolidinedione across the cell membrane, increased from 7.21 to 7.36. At a very high
blood glucose concentration (50 mmol/liter), the
tumor was isolated from the host, with almost total blockade of water,
chloride,
glucose,
lactate, and
dimethyloxazolidinedione exchange between the
tumor and the blood.
Hyperglycemia therefore represents a convenient means of isolating the
Yoshida sarcoma from the host blood supply to enable more selective treatment with
hyperthermia and possibly other modalities.