Potassium turnover and norepinephrine sensitivity in the thoracic aorta of the Dahl rat

This in vitro study evaluated the basal 42K turnover and response to norepinephrine (NE) in the thoracic aorta removed from Dahl salt-sensitive (S) and salt-resistant (R) rats. Five-week-old S and R rats were placed on either a high-salt (HS) or low-salt (LS) diet. After 5 weeks of the diet, systolic blood pressure, aortic weight/length ratio, and the cellular pool of K+ were elevated in the S-HS group only. In contrast, the steady state turnover of 42K, the NE ED50, and the response to a supramaximal dose of NE were the same in both groups of salt-sensitive and salt-resistant rats. These results suggest that, despite the presence of a greatly elevated systolic blood pressure and evidence of aortic hypertrophy, the intrinsic electrolyte metabolism of the vascular smooth muscle in the Dahl hypertensive rat is the same as that of the Dahl normotensive rat.