Stress, salt and hypertension.

In the Borderline Hypertensive Rat, a genetic model of NaCl sensitive hypertension, permanent hypertension may be produced by increased dietary NaCl intake or chronic environmental stress. Combining the interventions produces an additive/synergistic effect on arterial pressure. The hypertension is prevented by prior renal denervation, suggesting that stress-induced increases in renal sympathetic nerve activity contribute to the abnormal renal sodium retention by resetting of the arterial pressure-natriuresis relationship to a higher arterial pressure. In normal dogs, arterial pressure was not increased by either stress or NaCl alone but was by their combination. In subhuman primates, stress but not NaCl increased arterial pressure; arterial pressure was increased when stress was superimposed on NaCl but not by the reverse. In normal human subjects on combinations of normal or high NaCl intake with low or high stress, arterial pressure was increased only with the high NaCl-high stress combination. NaCl sensitivity of arterial pressure was increased by stress. The data suggest that stress-induced neurohumoral responses can potentiate the arterial pressure response to increased dietary NaCl intake.