Autonomic modulation of arterial pressure and heart rate variability in hypertensive diabetic rats

Authors

  • Vera de Moura Azevedo Farah Mackenzie University
  • Kátia De Angelis Sao Judas Tadeu University
  • Luis Fernando Joaquim University of Sao Paulo; School of Medicine of Ribeirao Preto
  • Georgia O. Candido University of Sao Paulo; Medical School; Heart Institute; Hypertension Unit
  • Nathalia Bernardes Sao Judas Tadeu University
  • Rubens Fazan Jr University of Sao Paulo; School of Medicine of Ribeirao Preto
  • Beatriz D'Agord Schaan University Foundation of Cardiology; Institute of Cardiology of Rio Grande do Sul
  • Maria-Claudia Irigoyen University of Sao Paulo; Medical School; Heart Institute; Hypertension Unit

DOI:

https://doi.org/10.1590/S1807-59322007000400015

Keywords:

Hypertension, Diabetes, Spectral Analysis, Cardiovascular Function, Baroreflex Sensitivity

Abstract

OBJECTIVE: The aim of the present study was to evaluate the autonomic modulation of the cardiovascular system in streptozotocin (STZ)-induced diabetic spontaneously hypertensive rats (SHR), evaluating baroreflex sensitivity and arterial pressure and heart rate variability. METHODS: Male SHR were divided in control (SHR) and diabetic (SHR+DM, 5 days after STZ) groups. Arterial pressure (AP) and baroreflex sensitivity (evaluated by tachycardic and bradycardic responses to changes in AP) were monitored. Autoregressive spectral estimation was performed for systolic AP (SAP) and pulse interval (PI) with oscillatory components quantified as low (LF:0.2-0.6Hz) and high (HF:0.6-3.0Hz) frequency ranges. RESULTS: Mean AP and heart rate in SHR+DM (131±3 mmHg and 276±6 bpm) were lower than in SHR (160±7 mmHg and 330±8 bpm). Baroreflex bradycardia was lower in SHR+DM as compared to SHR (0.55±0.1 vs. 0.97±0.1 bpm/mmHg). Overall SAP variability in the time domain (standard deviation of beat-by-beat time series of SAP) was lower in SHR+DM (3.1±0.2 mmHg) than in SHR (5.7±0.6 mmHg). The standard deviation of the PI was similar between groups. Diabetes reduced the LF of SAP (3.3±0.8 vs. 28.7±7.6 mmHg2 in SHR), while HF of SAP were unchanged. The power of oscillatory components of PI did not differ between groups. CONCLUSIONS: These results show that the association of hypertension and diabetes causes an impairment of the peripheral cardiovascular sympathetic modulation that could be, at least in part, responsible for the reduction in AP levels. Moreover, this study demonstrates that diabetes might actually impair the reduced buffer function of the baroreceptors while reducing blood pressure.

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Published

2007-01-01

Issue

Section

Basic Research

How to Cite

Farah, V. de M. A., De Angelis, K., Joaquim, L. F., Candido, G. O., Bernardes, N., Fazan Jr, R., Schaan, B. D., & Irigoyen, M.-C. (2007). Autonomic modulation of arterial pressure and heart rate variability in hypertensive diabetic rats . Clinics, 62(4), 477-482. https://doi.org/10.1590/S1807-59322007000400015