Sodium chloride preference in hypertensive (H) and normotensive (N) rats

Salt consumption was compared in two strains of rats, selected for their disparate proneness (strain "H") or resistance (strain "N") to Doca-salt hypertension. NaCl intake was similar in "H" and "N" rats prior to an following administration of Doca, while their respective blood pressures at the end of this experiment was 178±5 mm Hg vs. 134±3 mm Hg. Thus, disparate responses of the blood pressure to Doca in the two strains cannot be ascribed to differences in salt intake. In another study, salt preference was tested in "H" and "N" rats by two-bottle self-selecting technique. Before Doca, saline preference in "H" rats averaged 60.3±5.8% of total daily fluid consumption, vs 18±4.2% in "N" rats. Following Doca treatment for 3 weeks the respective values were 96±1.7%vs. 67±6.6%. Thus Doca treatment enhanced salt appetite in both strains, but salt preference remained significantly higher in the "H" rats. The increased susceptibility to hypertension and the enhanced salt appetite in the "H" rat, corroborates similar reports in the Okamoto "SH" rat. In the Brookhaven "S" rat, however, susceptibility to hypertension is associated with salt avoidance. The conflicting data do not support a unified concept of a genetically determined link between salt appetite and proneness to hypertension.