Once death was confirmed the pulmonary system was flushed with a heparin-solution (Wockhardt UK Ltd., Wrexham, UK) via catheter inserted into

the right ventricle or caudal vena cava. This was followed by Dublecco’s phosphate buffer solution (D-PBS, Sigma–Aldrich ABT-737 research buy Ltd., Gillingham, UK) to remove remaining blood from circulation. The lungs were inflated with around 3 ml of air and the trachea clamped; then the lungs, heart, and connective tissue were extracted en bloc. After extraction the lung’s trachea was cannulated and a syringe was used to breathe the lungs to ensure that they did not leak. Lungs were stored in glucose solution (5% glucose in water, Baxter Healthcare Ltd., Thetford, UK), chilled XL184 to approximately 280 K until needed. Excised rat lungs were inserted into a custom-made, sealable, ventilation chamber that filled the entire coil region. The ventilation chamber and its operating procedures are described in detail in previous work [15]. Briefly, the trachea of the rat lung was cannulated with an adaptor that was attached to the top of the ventilation chamber. The ventilation chamber was filled to about 2/3 of its total volume with a 5% glucose solution (Baxter Healthcare Ltd., Thetford, UK). Hp gas was delivered to the storage volume VB after compression using one of the two Extraction

Schemes described in this work. When a volume was pulled on the inhalation syringe pressure equalization forces the lungs to expand ( Fig. 8). This acts in a similar fashion to the thoracic diaphragm, as the expansion of the lungs causes it to inhale Fossariinae gas from the volume VB. Rubidium filters were made from 60 mm

of Teflon tubing (outer-diameter = 9.4 mm, inner-diameter = 6.4 mm; Swagelok, Warrington, UK) with 100 g of glass wool (Corning glass works, Corning, NY, USA) loosely packed inside. Chemical indicator paper (Whatman plc, Maidstone, UK) was used to check the pH value of the 1.0 ml of distilled water used to wash the glass wool. The resulting pH of the rubidium wash was pH 5.0. After SEOP at 220 kPa, a transfer of 5 s in duration resulted in a pressure of approximately 11 kPa of hp gas in Vext. Valves A + B ( Fig. 3a) were closed and the connecting lines were evacuated. A selected pressure of O2 gas was then added to Vext and the connecting lines were evacuated again. After a 5 s time delay that allowed for mixing of the O2 with the hp gas, the mixture was delivered for the MR measurements performed using Extraction Scheme 2. All T  1 data were obtained at ambient temperature using a pulse sequence comprising of sixteen medium (θ=12°)(θ=12°) flip angle r.f. pulses evenly separated by time increment τ. T1 relaxation values were determined from the nonlinear least-square analysis of the time dependence of the NMR signal intensity f(t) in the presence of spin-destruction due to the r.f.