The combined measurement of blood flow and metabolism in RIF‐1 tumours in vivo. A study using H₂ flow and ³¹P NMR spectroscopy

Blood flow and phosphorus metabolites have been measured simultaneously in the murine RIF‐1 tumour in vivo. Blood flow was measured using the H₂ washout technique and ³¹P NMR spectroscopy was used to measure high energy phosphates, inorganic phosphate and intracellular pH within the tumour. Following NMR and flow measurements, hydralazine was administered and the measurements repeated. There was always a decrease in blood flow, and a fall in nucleoside triphosphate detected by NMR, after administration of hydralazine. At blood flows in excess of 15 mL 100 g⁻¹ min⁻¹ the nucleoside triphosphate/inorganic phosphate ratio was 1.0 or greater, whereas at flows in the range of 5–12 mL 100 g⁻¹ min⁻¹ the ratio fell to below 0.5, and at flows below 5 mL 100 g⁻¹ min⁻¹ there was no detectable resonance from nucleoside triphosphate.