EFFECTS OF AUTONOMIC BLOCKADE ON NON-LINEAR CARDIOVASCULAR VARIABILITY INDICES IN RATS
Authors: Beckers, Frank; Verheyden, Bart; Ramaekers, Dirk; Swynghedauw, Bernard; Aubert, André E
Source: Clinical and Experimental Pharmacology and Physiology, Volume 33, Numbers 5-6, May/June 2006 , pp. 431-439(9)
Publisher: Blackwell Publishing
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Abstract:
SUMMARY • The present study assesses the effects of autonomic blockade (a- and b-adrenoceptor and cholinergic) on cardiovascular function studied by heart rate variability (HRV), blood pressure variability (BPV) and baroreflex sensitivity in rats using non-linear dynamics. Little is known about the influence of pharmacological autonomic nervous system interventions on non-linear cardiovascular regulatory indices. • In 13 conscious rats, heart rate and aortic blood pressure were measured continuously before, during and after autonomic blockade with atropine, phentolamine and propranolol. Non-linear scaling properties were studied using 1/f slope, fractal dimension and long- and short-term correlation. Non-linear complexity was described with correlation dimension, Lyapunov exponent and approximate entropy. Non-linear indices were compared with linear time and frequency domain indices. • b-Adrenoceptor blockade did not alter the non-linear characteristics of HRV and BPV, although low-frequency power of HRV was depressed. a-Adrenoceptor blockade decreased the scaling behaviour of HRV, whereas cholinergic blockade decreased the complexity of the non-linear system of HRV. For BPV, the scaling behaviour was increased during a-adrenoceptor blockade and the complexity was increased during cholinergic blockade. The linear indices of HRV and BPV were decreased. • The present results indicate that the b-adrenoceptor system has little involvement in the generation of non-linear HRV and BPV in rats. • a-Adrenoceptor blockade mostly influenced the scaling properties of the time series, whereas cholinergic blockade induced changes in the complexity measures. • The absence of the baroreflex mechanism can trigger a compensatory feed-forward system increasing the complexity of BPV.Keywords: autonomic nervous system; baroreflex; blood pressure; heart rate variability
Document Type: Research article
DOI: 10.1111/j.1440-1681.2006.04384.x
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