Acute Response to Elastase in Sheep Lungs

The early inflammatory changes in sheep's lungs were studIed with Ga-67 ci trate, Injected i.v. ImmedIately following intrabronchialinstIllatIonof different dosesof elastaseIntothe rightdIaphragmaticlobesof 15sheep.Theelastase-in duced lesionsIn the first five sheep (two received 4,000 unfts;three got 6,000) were imaged up to seven times in an 8-day period to measure the temporal changesin the lesionand to select the approprIateImagingtime; the other ten sheep (800-8,000 units) were imaged once at 52 hr. Localizationof Ga-67, as seen on the posterior and right lateral projections, was confined to a wefl-circum scrIbed region in the right lung field. The lesion could be detected as early as 4 hr after elastaseinstillation.It decreasedto 60% of its initialarea at 4 hr, while the total Ga-67 activfty in the sheep remained constant after 52-75 hr. Galllum-67 up take in the lesion correlated positivelywfth the dose of elastase (r 0.88, p <0.001) andwiththe reductioninperfusion,as determined4 wk afterthe elastase Instillation (r 0.66, p <0.05). Early Ga-67 uptake in Inflammatory lung lesions couldthereforebe usedas a reliablepredictorof the size of the acuteelastase. inducedinflammatoryreaction,as as of the sequeiaeinvolvingthe regional vascular supply 4 wk later.