Studies on Coenzyme Q Contents in Serum Lipoproteins

Part II. Changes in the Concentrations of Coenzyme Q₉ and α-tocopherol in Rats with Isoproterenol Induced Myocardial Necrosis

Abstract

Myocardial necrosis was induced experimentally by the method of Rona, and coenzyme Q₉ and α-tocopherol concentrations were measured in the serum and lipoprotein fractions. There was no significant change in the serum coenzyme Q₉ concentrations after isoproterenol administration. In contrast, the serum α-tocopherol levels decreased 6h and 12h after the administration, and the α-tocopherol-cholesterol ratio decreased within 12h. In control subjects, most of coenzyme Q₉ was distributed in the VLDL and LDL fractions, while most of α-tocopherol was present in the HDL fraction. The coenzyme Q₉ levels decreased 6h, 12h and 24h after isoproterenol administration in VLDL, and the lowest level was at 12h. On the other hand, the coenzyme Q₉ level elevated within 12h in the LDL fraction. The α-tocopherol level decreased rapidly in the VLDL fraction, reaching a minimum within 6h, and showed an increase at 12h in the LDL fraction. There was no significant change in the HDL fraction. The coenzyme Q₉-cholesterol ratio increased within 12h in the LDL fraction and within 6h in the HDL fraction. The α-tocopherol-cholesterol ratio decreased within 6h in the VLDL and HDL fractions, while there was no significant change in the LDL fraction. The coenzyme Q₉-α-tocopherol ratio increased within 6h in the VLDL and HDL fractions and within 12h in the serum and LDL fraction. These results indicate that the metabolism of coenzyme Q₉ is different from that of α-tocopherol in lipoproteins. It is concluded that coenzyme Q is mainly transported from VLDL (and chylomicron) to LDL at the onset of acute vascular accidents, for the lipase activity is stimulated by hormones, and then coenzyme Q is carried from LDL and HDL to mitochondria rich organs through the LDL receptor or other routes.