Platelets have been labeled with a new neutral, lipid-soluble metal complex of indium 111 (111In) and tropolone. Unlike oxine, which is soluble in ethyl alcohol, tropolone is soluble in isotonic saline. Platelet labeling with 111In tropolone can be performed in both acid-citrate-dextrose (ACD) plasma and ACD saline within two hours. Labeling efficiency has been 80% to 90%. 111In tropolone in ACD saline and ACD plasma at tropolone concentrations of 5 and 10 micrograms/ml, respectively, and incubation of the platelets with the tracer at room temperature for 20 minutes were optimal conditions for labeling. The authors have developed an ACD-saline kit for convenient preparation of 111In-labeled platelets. No adverse effect of 111In tropolone on platelets has been observed in studies of biodistribution, recovery, and survival of platelets in rabbits and dogs.

We have observed that pigs with Impaired platelet function in the form of severe von Wlllebrand's disease (vWd) are resistant to spontaneous and to diet-Induced aortic atherosclerosis. However, it has been reported that vWd pigs are susceptible to coronary atherosclerosis produced by balloon-Induced injury of coronary arteries combined with an atherogenlc diet. We have evaluated the development of coronary atherosclerosis in normal control (NC) and homozygous vWd pigs In two prospective studies: 1) as a spontaneous process In five NC and vWd pigs receiving a regular diet from the age of 3 months to 4 years; and 2) in nine NC and five vWd receiving a high-fat and high-cholesterol (2%) diet from the age of 3 to 9 months. All of the coronary arteries were analyzed postmortem In 5-mm sections. None of the NC nor the vWd pigs in the spontaneous study showed coronary atherosclerosis or myocardial lesions. In the study of diet-induced atherosclerosis, only one NC and one vWd pig had discrete stenoses; the stenoses affected the three coronary arteries and were significant (50% to 80%) In the NC and mild (>25%) In the vWd pigs; no pigs showed myocardial lesions. Pigs with vWd are resistant to atherosclerosis of the aorta. To assess the resistance or susceptibility to coronary disease In these pigs, a longer follow-up study would be necessary. (Arteriosclerosis 5:67-73, January/February 1985)