Increased calcium uptake in vascular tissue by plasma of salt induced hypertensive Dahl rats.

Elevated intracellular free cytosolic calcium in vascular smooth muscle cells has been suggested in the pathophysiology of hypertension and circulating factors in the plasma have been implicated. To investigate the role of these factors on calcium homeostasis in salt induced hypertension, calcium uptake was measured in aortae of Sprague-Dawley rats by plasma derived from Dahl salt sensitive and resistant rats given high (8.0%) and low (0.4%) salt diets, respectively, for four weeks. Calcium uptake was also measured in aortae of Dahl rats on these diets. Calcium uptake in aortae and systolic blood pressure were higher (P less than 0.001) in Dahl salt sensitive rats given a high salt diet as compared to those on a low salt diet. Plasma from salt sensitive rats on high salt diet increased calcium uptake (P less than 0.001) in aortae of Sprague-Dawley rats. In contrast, no changes in calcium uptake and systolic blood pressure were observed in Dahl salt resistant rats. The parallel increase in systolic blood pressure and calcium uptake in Dahl salt sensitive rats on high salt diet suggests that increased intracellular free calcium may be involved in the pathophysiology of hypertension. The increased calcium uptake seems to reflect an abnormality in calcium handling by the vessels. These data also demonstrate that plasma from salt sensitive rats on high salt diet increases calcium uptake in aortic tissue.