MP. Increased dietary salt intake enhances the exercise pressor reflex.

Increased dietary salt in rats has been shown to sensitize central sympathetic circuits and enhance sympathetic responses to several stressors, including hyperinsulinemia, intracerebroventricular injec-tion of angiotensin, and electrical stimulation of sciatic nerve affer-ents. These findings prompted us to test the hypothesis that increased dietary salt enhanced the exercise pressor reflex. Male Sprague-Dawley rats were fed 0.1 % (low) or 4.0 % (high) NaCl chow for 2 to 3 wk. On the day of the experiment, the rats were decerebrated, and the hind limb muscles were statically contracted for 30 s by electri-cally stimulating the cut peripheral ends of the L4 and L5 ventral roots. We found that contraction produced a significantly greater increase in mean arterial pressure of rats fed 4.0 % (n 26) vs. 0.1% (n 22) NaCl (24 2 vs. 15 2 mmHg, respectively; P 0.05). Baseline mean arterial pressure was not different between groups (0.1%, 77 4 vs. 4.0 % NaCl, 80 3 mmHg). Likewise, the tensio