Non-linear analysis of the cardiovascular control system in rat strains with differing hemodynamic characteristics

The objective of this study was to investigate the acute and chronic contribution of non-linear components to arterial blood pressure and sympathetic nerve activity in rat strains with differing basal sympathetic nerve activity (SNA) and arterial blood pressure (PB) levels. Experiments were performed in rats with differing hemodynamic characteristics. Rats were chronically instrumented with arterial and venous catheters and nerve electrodes placed around the sympathetic major splanchnic nerve. Various interventions, such as sympathetic and parasympathetic blockade, were performed. Largest Lyapunov exponent (LLE) and Correlation Dimension (CD) calculations were performed on obtained BP and SNA data. Autonomic interventions change the non-linear parameters. However, no significant difference in any non-linear parameter was found for the strains, i.e. the parameters failed to detect chronically elevated BP and sympathetic tones.