In vivo measurement of the disaggregatory action of prostacyclin. A methodological study.

The disaggregating effect of PGI2 was measured in a modified in vivo model described by Hornstra. The arterial blood of mongrel dogs was directed through an extracorporeal filter by a roller pump, and the pressure proximal to the filter was measured. The filter became spontaneously occluded mostly by aggregates of platelets within a few minutes, and as a result the pressure before the filter increased continuously. PGI2, administered either before the filter or intravenously, produced dose-related reduction in filtration pressure. Results obtained in control experiments revealed that the rate of platelet aggregation was reproducible; neither the count of platelets in the circulating blood nor the in vitro sensitivity of platelets to ADP and PGI2 changes significantly in the course of an experiment. The technique described seems to be useful to determine the disaggregatory potency of prostacyclin and other substances.