Prehypertensive changes in sodium transport induced by deoxycorticosterone acetate in incubated rat tail artery

The transport and distribution of sodium, potassium, and water were examined in tail arteries of rats treated with deoxycorticosterone acetate (DOCA)-saline for 10 days, a time that marks the earliest onset of a rise of blood pressure in the strain (Wistar) used. The arteries were incubated for more than 20 hours to ensure that any change observed was sufficiently built in so that it could not readily be washed out. Three distinct changes were observed. First, the steady state transmembrane sodium gradient (operationally [Na]o/[Na]i) was increased. Second, the amount of sodium excluded from participation in the sodium gradient, and hence probably bound, was increased. Third, after prolonged potassium depletion, the ouabain-insensitive loss of cell water and sodium that follows the readmittance of potassium was increased. These results suggest that fundamental embedded changes in sodium transport occur well before the blood pressure rises in response to DOCA-saline.