P-31-magnetic resonance spectroscopy and H-2-magnetic resonance imaging studies of a panel of early-generation transplanted murine tumour models

The objective of this study was first to determine whether three slowly gro wing early-generation murine transplantable tumours, the T40 fibrosarcoma, T115 mammary carcinoma and T237 lung carcinoma, exhibit patterns of energet ics and blood flow during growth that are different from those of the faste r growing RIF-I fibrosarcoma. Serial measurements were made with P-31-magne tic resonance spectroscopy (MRS), relating to nutritive blood flow and H-2- magnetic resonance imaging (MRI), which is sensitive to both nutritive and large-vessel (non-nutritive) flow. All four tumour lines showed a decrease in beta NTP/P-i and pH with growth; however, each line showed a different p attern of blood flow that did not correlate with the decrease in energetics . Qualitative histological analysis strongly correlated with the H-2-MRI. S econd, their response to 5 mg kg(-1) hydralazine i.v. was monitored by P-31 -MRS. A marked decrease in beta NTP/P-i and pH was observed in both the RIF -I fibrosarcoma and the third-generation T115 mammary carcinoma after hydra lazine challenge, In contrast, the fourth generation T40 fibrosarcoma and T 237 lung carcinoma showed no change in 31P-MRS parameters. However, a fifth -generation T237 cohort, which grew approximately three times faster than f ourth-generation T237 cohorts, exhibited a significant deterioration in bet a NTP/P-i and pH in response to hydralazine. These data are consistent with a decoupling between large-vessel and nutritive blood flow and indicate th at early-generation transplants that have a slow growth rate and vascular t one are more appropriate models of human tumour vasculature than more rapid ly growing, repeatedly transplanted tumours.