Renal denervation in an animal model of diabetes and hypertension: impact on the autonomic nervous system and nephropathy.

BACKGROUND

The effects of renal denervation on cardiovascular reflexes and markers of nephropathy in diabetic-hypertensive rats have not yet been explored.

AIM

To evaluate the effects of renal denervation on nephropathy development mechanisms (blood pressure, cardiovascular autonomic changes, renal GLUT2) in diabetic-hypertensive rats. Forty-one male spontaneously hypertensive rats (SHR) ~250 g were injected with STZ or not; 30 days later, surgical renal denervation (RD) or sham procedure was performed; 15 days later, glycemia and albuminuria (ELISA) were evaluated. Catheters were implanted into the femoral artery to evaluate arterial pressure (AP) and heart rate variability (spectral analysis) one day later in conscious animals. Animals were killed, kidneys removed, and cortical renal GLUT2 quantified (Western blotting).

RESULTS

Higher glycemia (p < 0.05) and lower mean AP were observed in diabetics vs. nondiabetics (p < 0.05). Heart rate was higher in renal-denervated hypertensive and lower in diabetic-hypertensive rats (384.8 +/- 37, 431.3+/- 36, 316.2 +/- 5, 363.8 +/- 12 bpm in SHR, RD-SHR,STZ-SHR and RD-STZ-SHR, respectively). Heart rate variability was higher in renal-denervated diabetic hypertensive rats (69.84 ± 37.91, 55.75 ± 25.21, 73.40 ±53.30, 148.4 ± 93 in SHR, RD-SHR, STZ-SHR- and RDSTZ-SHR, respectively, p < 0.05), as well as the LF component of AP variability (5.17 ± 5.24, 1.62 ± 0.9, 2.12 ±0.9, 7.38 ± 6.5 in SHR, RD-SHR, STZ-SHR and RDSTZ-SHR, respectively, p < 0.05). GLUT2 renal content was higher in all groups vs. SHR [corrected].

CONCLUSIONS

Renal denervation in diabetic-hypertensive rats improved previously reduced heart rate variability. The GLUT2 equally overexpressed by diabetes and renal denervation may represent a maximal derangement effect of each condition.