Abstract 553: High-Intensity Interval Training Partly Restores Thrombotic Microangiopathy in an Experimental Model of Hypertensive Renal Injury

To investigate whether high intensity interval training can reduce hypertensive renal injury in Dahl salt-sensitive rats. Adult females Dahl salt-sensitivity (Dahl SS) rats were randomized in three groups: sedentary low-salt diet (LS, N=20: 0.3% NaCl), sedentary high-salt diet (HS, N=40: 8% NaCl) or high-salt diet submitted to high intensity interval training (HIT, N=20: 8% NaCl + HIT, 3x38 min/wk; 60% HRmax adding 4 intervals of 4 min at 90% HRmax). After 30 weeks of follow-up, 24h urine has been collected in metabolic cages, followed by tissue harvesting. HIT did not affect the development of hypertension induced by high-salt intake in the Dahl SS rats (147±55 vs 209±80* vs 203±79* mm Hg, for LS, HS and HIT, respectively; *p<0,05 compared to LS). However, total mortality was significantly reduced (p=0.0022) in the HIT group (8/20 events) compared to HS (23/40 events) and LS (1/20 events) groups (94.7% vs 39.9% vs 59% survival, for LS, HS and HIT respectively), most of the deaths caused by stroke (69.6% incidence in HS rats). Chronic high blood pressure caused microalbuminuria that was not reverted by exercise (0.65±0.34 vs 95±42* vs 72±37* mg/24h, for LS, HS and HIT, respectively; *p<0.05 compared to LH). Creatinine clearance was not changed by either hypertension or exercise (1.91±0.58 vs 1.73±0.85 vs 1.60±0.66 ml/min, for LS, HS and HIT, respectively; p=0.53). Histological analysis of the renal injury reveled that HIT did not reverse the expansion of mesangial matrix (125±40 vs 179±44* vs 188±47*, for LS, HS and HIT, respectively; *p<0.05 compared to LS) and no glomerulosclerosis were detected (69±36 vs 97±36 vs 117±57, for LS, HS and HIT, respectively; p=0.12). Interesting, HIT significantly reduced (7/10) the number of nephrons with thrombotic microangiopathy observed in the HS (10/11) compared to LS (0/15) group (0.00±0.00 vs 8.82±2.82* vs 6.60±3.06 counts/kidney, for LS, HS and HIT, respectively; *p<0.05 compared to LS). Taken together our data demonstrate that, although no changes have been observed in the hypertension status and microalbuminuria, HIT partially reverted the high thrombotic microangiopathy incidence in the Dahl salt model, and may explain the reduction in the mortality caused by stroke.