Genetic difference in the sympathetic nervous activity and susceptibility to atherosclerosis in pigeon

Norepinephrine (NE) accumulation, dose response to NE and NE content were studied in the aortas of White Carneau (WC) and Show Racer (SR) pigeons in order to determine if a correlation exists between the atherosclerosis susceptibility of WC and atherosclerosis resistance of SR with the degree of sympathetic nerve ending activity. In addition, the age factor was included by comparing results in 4-14 month-old and 5-year-old animals. NE accumulation by abdominal aorta samples from SR pigeons of both age groups and by thoracic segments from 5-year-old SR was significantly higher than that by WC pigeon samples. The difference in NE accumulation had lower P-values in older than in younger pigeons. Maximal contraction of SR abdominal aorta was significantly higher than that of WC samples. The ED50 to exogenous NE decreased with age in both strains but the decrease was statistically significant only in WC strain. Finally, NE content of abdominal aorta segments was significantly higher in SR than in WC pigeons. Ne content of thoracic aorta did not differ in the 2 strains. The results complement our previous work indicating that sympathetic nerve endings in the vessel wall may have a trophic influence which modulates the metabolic pattern of the arteries. Thus, atherosclerosis and perhaps age, are related degenerative vascular changes associated with reduced indices of sympathetic activity.