Joint order pattern analysis to assess baroreflex coupling of SBP and PI series in rats

The baroreceptor reflex (BRR) bears the important part in short term blood pressure (BP) control. Joint order pattern analysis is proposed to assess the complex nature of BP and pulse interval (PI) dynamic. The BP and PI signals were acquired from conscious radiotelemetred Wistar male rats with intact BRR loop and pharmacologically opened BRR loop at different levels using blockade of β-adrenergic, α-adrenergic and M-cholinergic receptors. The study revealed increase in complexity of relationship between BP and PI due to opening of BRR loop, as measured by permutation entropy and probability density function of transcriptions translating BP variations into PI responses. Synchronization measure significantly decreases in open BRR loop changing from 0.22 towards the values characteristic for random and independent data (0.02). It follows that BRR buffers random BP and PI changes and increases their synchronization.