Dose-dependent inversion of the effect of prostaglandin E1 on intraosseous pressure: adequate dose for reducing blood loss during operation on bone.

Abstract

Tibial intraosseous pressure and blood flow, along with arterial pressure, were measured in anesthetized rabbits before and during intravenous infusion of prostaglandin E1 at doses of 0, 100, 300, 1000, and 2000 ng/kg per min. The mean arterial pressure decreased dose-dependently. The intra-osseous pressure increased during infusion at doses of 300 and 1000 ng/kg per min, but decreased during infusion at the dose of 2000 ng/kg per min. Bone blood flow increased during infusion only at a dose of 1000 ng/kg per min. Calculated vascular and arteriolar resistances in bone decreased dose-dependently during infusion at doses of up to 1000 ng/kg per min, but no change was seen when the dose was increased from 1000 to 2000 ng/kg per min. These findings indicated that: (1) there was a turning point in the effect of prostaglandin E1 at a certain dose between 1000 and 2000 ng/kg per min, at which the arterioles in bone were fully dilated; (2) at a dose of 1000 ng/kg per min or lower, responsive dilatation in the arterioles of bone under mild arterial hypotension increased the influx of blood into the bone, thereby increasing the intraosseous pressure; and (3) at doses higher than 1000 ng/kg per min, dose-dependent arterial hypotension without further dilatation in the arterioles of bone decreased the influx of blood.