TURNOVER OF TPA IN RABBITS - INFLUENCE OF CARBOHYDRATE MOIETIES

The turnover of tissue plasminogen activator (tPA) was studied in rabbits using a double-label technique which allowed the comparison of various tPA derivatives with a standard tPA in individual animals. Purified recombinant tPA (Alteplase) was labelled with 125I and used as a standard for each experiment. Various tPA preparations which lacked specific carbohydrate structures were labelled with 131I (in separate experiments) and injected along with the 125I-tPA standard into rabbits. The clearance of standard tPA was biphasic with an average T1/2.alpha. and T1/2.beta. of 0.85 min and 12 min respectively. Type II tPA which lacks a portion of carbohydrate associated with Type I tPA as well as desialated tPA demonstrated a longer T1/2.beta. than standard tPA.