A pressure chamber for removing cryobiopsies from small laboratory animals.

A pressure chamber for small laboratory animals was designed that can be operated up to 4 bar. It enables the removal of tissue cryobiopsies at liquid nitrogen temperatures during pressurisation. Relevant systemic parameters of the animals investigated, such as mean arterial blood pressure or rectal temperature, can be monitored throughout the experiments. In addition, intravenous infusions of blood, blood substitutes or drugs can be administered. The main goal of constructing the chamber presented is the investigation of tumour oxygenation under hyperbaric conditions. This is performed by measuring the oxyhaemoglobin saturation (HbO2) of single red blood cells in tumour microvessels using a cryophotometric micromethod. In a preliminary series of experiments with rats bearing DS-carcinosarcoma it could be demonstrated that the present experimental set-up leads to HbO2 values in solid tumours which are in accordance with results obtained from previous investigations during exposure to normal air using a different sampling technique.