Mechanisms of the Genetic Control of Plasma Cholesterol in Selected Lines of Show Racer Pigeons 1

Summary

Cholesterol absorption, synthesis, and turnover were studied in selected lines of hypo- and hyperresponder Show Racer pigeons by feeding a diet containing [³H]cholesterol and injecting a [¹⁴C]choles-terol-labeled serum. The decline in plasma [¹⁴C]cholesterol specific activity with time was analyzed according to a two-pool model.

The mass of cholesterol in pool A was higher in the hyperresponder line than in the hyporesponders, reflecting mainly plasma cholesterol differences of 1417-2253 mg/dl in the former compared with 319-457 mg/dl in the latter. No strain differences were found for the rates at which new cholesterol appeared in pool A, but the rate constant describing removal of cholesterol from that pool was higher for the hyporesponder line, signifying genetic control of plasma cholesterol at the level of excretion. Cholesterol absorption was calculated as 58 mg/day in the hyperresponders and 48 mg/ day in the hyporesponders, while endogenous synthesis was 12 and 28 mg/day, respectively.

The authors would like to thank Dr. L. Rhyne for assistance in the statistical procedures and Mr. J. Rodden and Mrs. C. Hine for excellent technical assistance.