An Observation of Thromboxane A2 in Arterial Blood after Cholesterol Feeding in Rabbits

Abstract

Agents responsible for the entry of cholesterol-bearing lipoproteins into the arterial wall represent local risk factors in atherogenesis. In an attempt to identify these agents, a catheter was inserted into the ascending aorta of rabbits and 5 ml of arterial blood sample was withdrawn. The aortic strip contraction of rabbit against Piper and Vane''s antagonists with application of this sample was observed. Samples obtained after feeding of 1 g/kg of cholesterol and after an i.v. administration of thromboxane A2 (TXA2) contracted the aortic strip. Samples from non-treated rabbits or those obtained after i.v. administration of 10 .mu.g of epinephrine or norepinephrine did not contract the strip. Previous administration of 20 mg/kg of indomethacin decreased the contraction developed after feeding of 1 g/kg of cholesterol. TXA2 might be released into the arterial blood by the ingestion of cholesterol and might be one of the agents responsible for the entry of lipoproteins.