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Sex differences in baroreflex sensitivity, heart rate variability, and end organ damage in the TGR (mRen2) 27 rat

MS Johnson, VG De Marco... - American Journal of ..., 2011 - Am Physiological Soc The aim of this investigation was to evaluate sex differences in baroreflex and heart rate variability (HRV) dysfunction and indices of end-organ damage in the TG(m Ren2)27 (Ren2) rat, a model of renin overexpression and tissue renin-angiotensin-aldosterone system (RAAS) over- ...

The aim of this investigation was to evaluate sex differences in baroreflex and heart rate variability (HRV) dysfunction and indices of end-organ damage in the TG(m Ren2)27 (Ren2) rat, a model of renin overexpression and tissue renin-angiotensin-aldosterone system (RAAS) over-activation. Blood pressure (via telemetric monitoring), blood pressure variability (BPV; standard deviation of systolic blood pressure [SDSBP]), spontaneous baroreflex sensitivity (s BRS), HRV (HRV Triangular Index [HRV-TI], standard deviation of the average NN interval [SDNN], low and high frequency power [LF and HF, respectively], and Poincaré plot analysis [SD1, SD2]), and cardiovascular function (pressure-volume loop analysis and proteinuria) were evaluated in male and female 10-week old Ren2 and Sprague Dawley (SD) rats. The severity of hypertension was greater in Ren2 males (R2-M) than in Ren2 females (R2-F). Increased BPV, suppression of baroreflex gain, decreased HRV, and associated end organ damage manifested as cardiac dysfunction, myocardial remodeling, elevated proteinuria, and tissue oxidative stress were more pronounced in R2-M compared to R2-F. During the dark cycle, HRV-TI and SDNN were negatively correlated with SBP within R2-M and positively correlated within R2-F; within R2-M, these indices were also negatively correlated with end organ damage (left ventricular hypertrophy [LVH]). Further, within R2-M only, LVH was strongly correlated with indices of HRV representing predominantly vagal (HF, SD1), but not sympathetic (LF, SD2) variability. These data demonstrated relative protection in females from autonomic dysfunction and end organ damage associated with elevated blood pressure in the Ren2 model of hypertension.