No abstract

No abstract

Summary.-Rubidium-86, 125I-human serum albumin and 5'Cr-labelled red cells have been used to investigate the effects of the anaesthetics Nembutal (pentobarbitone sodium) and urethane on blood perfusion, blood volume and albumin leakage in 5 types of transplanted mouse tumour and in normal organs. Nembutal was found to increase the relative blood perfusion by a factor of 1-3 to 2-0 in tumours and by a factor of 1*7 to 3-0 in kidneys but muscle perfusion fell to 0-3-0.5 that of controls.The effects of urethane were found to be dose dependent, generally in the same direction as for Nembutal, and smaller. Both anaesthetics reduced the blood volume of tumours (except for the C3H mammary carcinoma) and of kidneys by factors of 0-2 to 0-8. The duration of anaesthesia had no effect on the plateau values of relative blood perfusion and blood volume in either tumours or normal organs, but Nembutal delayed slightly the 86Rb uptake and decreased the rate of albumin leakage.

In anesthetized rabbits we measured clearance from lung to blood of eight aerosolized technetium-99m-labeled compounds: diethylenetriaminepentaacetate (99mTc-DTPA); cytochrome c; myoglobin; a myoglobin polymer; albumin; and anionic, cationic, and neutral dextrans of equivalent molecular size. We investigated the effect of applying positive end-expiratory pressure (PEEP) and, on a subsequent occasion, of injecting oleic acid intravenously to produce acute lung injury on the pulmonary clearance rate. Base-line clearance rates were monoexponential and varied with the molecular weights of the radiotracers. For each tracer the rate of clearance was increased a similar degree by either PEEP or oleic acid. However, with PEEP, clearance remained monoexponential, whereas after oleic acid, smaller molecular-weight radiotracers had multiexponential clearance curves. This suggests that after oleic acid the alveolar epithelium breaks down in a nonuniform fashion. We conclude that differentiation of the effect of PEEP from that of severe lung injury caused by oleic acid is not readily accomplished by either increasing the size of the tracer molecule or by varying the molecular charge.

No abstract