Prostaglandin E2 synthesis in pigeon aorta: comparison of atherosclerosis-resistant (Show Racer) and atherosclerosis-prone (White Carneau) breeds.

Microsomes prepared from the brachial artery and the thoracic aorta of atherosclerosis resistant (AR) Show Racer and atherosclerosis prone (AS) White Carneau pigeons were incubated with 14C-prostaglandin endoperoxide (PGH) and prostaglandin products analyzed. The microsomes demonstrated minimal prostacyclin (PGI2) synthetase activity; 6-keto-PGF1 alpha (the hydrolytic breakdown product of PGI2) accounting for less than 2% of total products. Reduced glutathione enhanced PGE2 formation in both the AR and AS preparations identifying an active PGH-PGE isomerase. The AR preparations demonstrated increased PGH-PGE formation with age, reaching maximal activity at 8-9 months, then decreasing at 14 months. The AS group also demonstrated a similar pattern of enzyme activity. These studies indicate that a) unlike the mammalian preparations prostacyclin synthetase does not appear to be a major enzymatic activity of the pigeon aorta, rather, b) PGH-PGE isomerase is the major endoperoxide metabolizing activity in the pigeon aorta and thus, c) a deficiency of prostacyclin production is not involved in the geneis of atherosclerosis in the pigeon.