Vascular tissue (Na,K)ATPase activity and aging in the F344 rat

Vascular tissue (heart, thoracic aorta and tail artery) was removed from Fischer 344 rats, 12, 18 and 27 months of age. The intact tissue was then used to determine total, ouabain-sensitive and ouabain-insensitive 86Rubidium (86Rb) uptakes, to provide a reflection of (Na,K)ATPase activity. These studies indicate no change in total, ouabain-sensitive nor ouabain-insensitive 86Rb uptakes into cardiac tissue isolated from these rats. However, tail artery total and ouabain-sensitive 86Rb uptake decreased with age (a 61% decrease in ouabain-sensitive 86Rb uptake in 12 vs. 27-month-old rats) without significant changes in the ouabain-insensitive 86Rb uptake. This pattern was repeated in aortic tissue with a 56% decrease in ouabain-sensitive 86Rb uptake in 12 vs. 27-month-old rats. The results of these studies support an age-related decline in (Na,K)ATPase activity in aortic and tail artery tissue without a significant change in cardiac (Na,K)ATPase activity between 12, 18 and 27-month-old Fischer 344 rats.