Apoptosis signal-regulating kinase 1 deficiency eliminates cardiovascular injuries induced by high-salt diet

OBJECTIVES: High-salt diet is closely associated with the increase in cardiovascular events. However, the mechanism of high-salt-induced cardiovascular injury is unknown. The present study was undertaken to test our hypothesis that apoptosis signal-regulating kinase (ASK) 1 may be involved in salt-induced cardiovascular injury. METHODS: Wild-type and ASK1-/- mice were fed a low-salt or a high-salt diet for 10 weeks and the effects of high-salt diet on food intake, urinary volume and electrolyte excretion, and cardiovascular injury were compared between both groups of mice. RESULTS: High-salt diet in wild-type and ASK1-/- mice similarly increased food intake, water intake, urine volume, and urinary sodium excretion, and comparably decreased plasma renin activity and aldosterone. Thus, ASK1 appears to play a minor role in the increase in natriuresis and the decrease in plasma renin, and aldosterone caused by high-salt diet. High-salt diet enhanced the phosphorylation of cardiovascular ASK1 in wild-type mice. High-salt diet in wild-type mice enhanced cardiac transforming growth factor-β1, interstitial fibrosis, coronary perivascular fibrosis, and inflammatory cell infiltration, and these changes were associated with the increase in cardiac superoxide and Nox2. ASK1 deficiency abolished the above-mentioned high-salt-induced cardiac injury. High-salt diet also caused the impairment of vascular endothelium-dependent relaxation by acetylcholine and increased vascular superoxide, and Nox2 in wild-type mice, whereas it did not cause vascular injury in ASK1-/- mice. CONCLUSION: ASK1 is implicated in cardiac inflammation and fibrosis, and vascular endothelial dysfunction caused by high-salt diet, through the enhancement of oxidative stress.