Effect of x-irradiation of tumour bed on tumour blood flow and vascular response to drugs.

The blood flow of tumours growing in rat mammary glands previously exposed to 1500 R X-rays was 52% that of same-sized tumours in unirradiated host tissue. About 2 months after irradiation, the blood flow of the mammary gland was raised and that of the skin was unchanged, compared with the corresponding unirradiated tissue. Tumours growing in preirradiated and unirradiated mammary glands responded similarly to bolus injections of noradrenaline, angiotensin II, and isoprenaline. The responses of the irradiated tissues to these drugs were, however, not always the same as those of the corresponding unirradiated tissues. Exposure of the lungs to approximately 1500 R X-rays made the animals uniquely sensitive to bolus injections of noradrenaline and angiotensin II.