Reduced Sympathetic Stimulus and Angiotensin 1-7 Are Related to Diastolic Dysfunction in Spinal Cord-Injured Subjects

Chronic spinal cord injury (SCI) is often associated with reductions in left ventricular (LV) diastolic function. Impairments in sympathetic activity and activation of the renin-angiotensin system are reported in SCI individuals and may hypothetically be implicated in this association. Hence, the present study verified the relationship between these two neuro-hormonal and cardiac functional and structural characteristics in SCI individuals. Twenty-two men with SCI (injury level above T6 and no voluntary motion below the injury) and 11 able-bodied men were evaluated by clinical, hemodynamic, laboratory, and echocardiographic analysis and had plasmatic renin, angiotensin I (ANGI), angiotensin II (ANGII), angiotensin 1-7 (ANG1-7), and noradrenaline levels measured. SCI subjects had lower noradrenaline (p = 0.003) and higher ANG1-7 (p = 0.009), but similar renin, ANGI, and ANGII levels when compared with able-bodied individuals. In SCI individuals, results of multi-variable analysis showed that higher Em, a marker of better LV diastolic function, was directly associated with ANG1-7 (p = 0.05) or ANG1-7/ANGII ratio (p = 0.007), whereas lower noradrenaline levels were independently associated with worse LV diastolic function, as assessed by E/Em ratio (p = 0.028). In conclusion, these results suggest that reduced sympathetic activity and expression of ANG1-7 may be involved in SCI-related diastolic dysfunction.