Contribution of salt to arterial wall changes in DOCA hypertension in the rat

The contribution of drinking fluid salt to the development of deoxycorticosterone (DOCA) hypertension and arterial wall changes was assessed in unilaterally nephrectomized rats. Half of the DOCA-treated animals received saline supplemented with 0.2% KCl and the other half received deionized water as drinking fluid. All animals were fed standard rat chow (Na content = 0.36%). After 8 weeks, arterial pressures were significantly elevated in both DOCA groups to values which were not significantly different. The heart weight to body weight ratio was also elevated in both DOCA groups with a larger response in the saline-treated ones. Body weight of saline-treated DOCA rats was significantly lower than untreated controls and water-treated DOCA rats. Arteries from both DOCA groups exhibited increased passive stiffness, larger maximum active stress, wall thickening, decreased collagen and elastin concentration, greater relative cell volume, and greater water and cation concentrations. Larger changes were generally found in the saline- than the water-treated group. These results show that saline administration is not necessary for the development of hypertension or hypertension-induced arterial wall changes in DOCA-treated, uninephrectomized rats. Hypertension developed more slowly and arterial wall changes were similar in magnitude in water-treated animals. These results suggest that the rate and/or time history of pressure elevation may be an important factor contributing to hypertension-related arterial changes.