An observation of thromboxane A2 in arterial blood after cholesterol feeding in rabbits.
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identify these agents, we inserted a catheter into the ascending aorta of rabbits and 5 ml of arterial blood sample was withdrawn. The contraction of the aortic strip of rabbit against Piper and Vane's antagonists with application of this sample was observed. Samples obtained after feeding of 1 Gm/Kg of cholesterol and after an intravenous administration of thromboxan A2 (TXA2) contracted the aortic strip. Samples from non-treated rabbits or those obtained after intravenous administration of 10 microgram 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 Gm/Kg of cholesterol. It was suggested that TXA2 might be released into the arterial blood by the ingestion of cholesterol and might be one of the agents repsonsible for the entry of lipoproteins.
D000818:Animals; D001011:Aorta; D002784:Cholesterol / Q000097:blood; D002791:Cholesterol, Dietary / Q000008:administration & dosage*; D004837:Epinephrine / Q000494:pharmacology; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D011817:Rabbits; D013928:Thromboxane A2 / Q000097:blood* / Q000494:pharmacology; D013931:Thromboxanes / Q000097:blood*; D014661:Vasoconstriction / Q000187:drug effects*
D002791:Cholesterol, Dietary; D013931:Thromboxanes; D013928:Thromboxane A2; D002784:Cholesterol; D009638:Norepinephrine; D004837:Epinephrine