Elevation of arterial phosphofructokinase activity associated with susceptibility to atherosclerosis in pigeons

Abstract

The activity of phosphofructokinase (PFK, 2.7.1. 11) was measured in arteries of very young (5–8 week old) pigeons known to differ in susceptibility to atherosclerosis. The activity of the arterial enzyme was significantly higher in the atherosclerosis susceptible White Carneau (WC) pigeons than in the resistant Show Racers (SR). The difference was significant whether enzyme activity was calculated on the basis of extract protein, DNA content or fat-free dry weight. In the White Carneau arteries the activity of the enzyme was higher in the female than the male pigeons. PFK is a key regulatory enzyme of glycolysis and is subject to fine control adjustments. A low ATP/ADP ratio and a fall in citrate concentration, as, for example, induced by hypoxia, are mediators of a feedback mechanism leading to a rise in PFK activity and enhancement of glycolysis for energy production. This mechanism appears to be the cause of the higher PFK activity in the WC arteries, because related studies indicate impaired Krebs cycle activity in these vessels. It is suggested that the increased dependence of the WC arteries on glycolysis facilitates the development of atherosclerosis in this pigeon strain and that the mechanism is similar to the mechanism by which tissue hypoxia causes lipid accumulation and connective tissue alterations in the arterial wall.