In Vitro Interaction between Venous Blood Clots and Radiopharmaceuticals

Summary

Clots of 1 ml venous blood formed in glass tubes after 10 min at room temperature were incubated at 37° C with the radiopharmaceutical to be studied. Methods for quality control of the radiopharmaceuticals were compared. Gel chromatography scanning was found to give reliable information. The incorporation into the clot was studie’d at different pH values and after various time intervals. The highest incorporation was found for ¹²⁵I-fibrinogen and for ^99mTc-mac-roaggregates of albumin, followed by ^99mTc-sulphur colloid and ^99mTc-strep-tokinase at pH less than 2. The titrated initial dose of ^99mTc-streptoki-nase was studied at various pH levels. The lysing effect was less in the pH range 1-2.5, where the best labeling yield was obtained. The inactivation of streptokinase by the labeling procedure was also studied with im-munoelectrophoresis and decomposition of casein. In vitro studies of the interaction of radiopharmaceuticals with clots add information for the clinical use of radiopharmaceuticals for thrombus localization.

Zusammenfassung

Gerinnsel aus 1 ml venosem Blut wurden in Glasröhrchen nach 10 min bei Raumtemperatur gebildet und bei 37° C mit dem zu untersuchenden Radiopharmazeutikum inkubiert. Methoden der Qualitätskontrolle von Radiopharmazeutika wurden verglichen. Gelchromatographie-Scanning ergab zuverlässige Informa-tionen. Die Inkorporation in den Blut-pfropfen wurde bei unterschiedlichen pH-Werten und nach verschiedenen Zeitabständen untersucht. Die höch-ste Inkorporation fand sich bei ¹²⁵J-Fibrinogen und bei ^99mTc-Makroaggregaten von Albumin, gefolgt von ^99mTc-Schwefelkolloid und ^99mTc-Streptokinase bei einem pH <2. Die titrierte Initialdosis von ^99mTc-Strepto-kinase wurde bei verschiedenen pH-Werten untersucht. Der Lyseeffekt war geringer im pH-Bereich 1-2,5, wo die besten Markierungsausbeuten er-halten wurden. Die Inaktivierung von Streptokinase durch das Markierungs-verfahren wurde auch mit der Immun-elektrophorese und anhand des Abbaus von Kasein untersucht. In-vitro-Untersuchungen der Interaktion von Radiopharmazeutika mit Blutgerinnseln ergaben zusätzliche Informationen zur klinischen Anwendungen von Radiopharmazeutika zur Lokalisation von Thromben.

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