Evaluation of non-linearities in the blood pressure signal of a WKY rat

The surrogate data method was applied in order to test the existence of nonlinear components in the blood pressure (BP) time series, recorded from a one month old conscious normotensive rat (WKY). The surrogate data was generated by producing five new data sets from the original BP time series. The correlation dimension of each of these time series was calculated. Two scaling regions were found in the original time series, whereas, in the surrogate data, one of these two regions was consistently missing. As for the second scaling region, a significant difference was found between the correlation dimension computed for the original time series and that of the different surrogate data sets. The authors´ results thus strongly indicate that there are nonlinear components in the BP time series taken from a WKY rat.<>