1. The contractile responses of aortic ring preparations from Sprague‐Dawley rats made hypertensive by 6‐week dietary salt loading were studied. The test and control diet contained 8.0 and 0.3% NaCl, respectively. Aortic rings from salt‐loaded rats showed enhanced sensitivity to nor‐adrenaline (NA) but not to serotonin. Contractile responses to CaCl₂ in Ca‐free NA‐containing medium was significantly enhanced in salt‐loaded rats, but was unchanged in K+‐depolarised medium. K+induced relaxation (a functional indicator of Na‐K adenosine triphosphatase activity) was sensitive to 10 μmol/L ouabain and was significantly attenuated in aortic rings from salt‐loaded rats. The results suggest that hypertension induced by salt‐loading is associated with enhanced sensitivity to NA, increased Ca²⁺ entry through receptor‐operated channels, and impairment of Na‐K ATPase enzyme activity.