Effects of oophorectomy on interstitial fluid pressure, blood flow and vascularity in a rat mammary tumour.

Interstitial fluid pressure (IFP), tumour size, blood flow and vascularity were measured in dimethyl-benz-alpha-anthracene-induced rat mammary tumours after oophorectomy. IFP was measured in the tumours by the wick-in-needle technique, blood flow by the labelled microsphere technique and vascularity by fluorescence vascular staining. Tumour volume was determined by measuring two diameters. Oophorectomy resulted in a decrease in tumour volume preceded by a decrease in IFP, while no significant change was observed in total tumour blood flow. The vascular cross-sectional area seemed to decrease. Cell proliferation may be of importance for the high interstitial fluid pressure in this hormone dependent tumour. A reduced metabolic requirement in the regressing tissue, down-regulating the vascular capacity, may camouflage the influence of the reduced tissue pressure on blood perfusion.