Diet-induced atherosclerosis in rabbits alters vascular prostacyclin release

Atherosclerosis is complicated by thrombosis and it has been suggested that a decreased prostacyclin and/or an increased thromboxane release from the vascular wall could play a part in this process. There are few reports dealing with determinations of prostanoid release from physiologically perfused normal and atherosclerotic vessel walls or from perfused atherosclerotic hearts. Therefore, fourteen rabbits were given 2% cholesterol added to the diet for 26 weeks, which led to atherosclerosis, verified by scanning electron microscopy. Five animals died, and in the surviving nine, as well as from ten healthy rabbits, the aorta was excised. The vessels were perfused with pulsatile flow at physiologic pressure five times for fifteen minutes with the addition of arachidonic acid to the last perfusate. Prostacyclin and thromboxane were determined as their stable degradation products 6-keto-PGF1 alpha and TxB2 by radio-immuno assay. Atherosclerotic and normal animals had the same initial release of prostacyclin but in the atherosclerotic animals the release did not decline with time as it did in the normal animals. The response to arachidonic acid was also higher in the atherosclerotic group. The release of thromboxane was not altered in the atherosclerotic group compared to the control group. It is concluded that prostacyclin release from aortas is altered in rabbits with diet-induced atherosclerosis compared to normal rabbit aortas, but that vascular thromboxane production is not.