Autonomic mediation in the interdependences between cardiocortical activity time variations and between cardiorespiratory activity time variations in the lizard, Gallotia galloti

Multivariate nonlinear analysis methods were applied to variability time series extracted from electrocardiographic, electrocorticographic and respiratory activities of Gallotia galloti lizards, to study interdependences between cardio-cortical activity time variations, and between cardio-respiratory activity time variations. Autonomic nervous system involvement in the mediation of such interdependences was investigated through pharmacological blockade. Cardiac variability was evaluated from the R–R intervals of the electrocardiogram (RRIv). Cortical (CORTv) and respiratory (RESPv) activity time variations were evaluated from power-data signals derived from both electrocorticogram and respiratory signal segments obtained within each R–R interval, respectively. A nonlinear index N to measure interdependence between the signals, and a surrogate data test to measure the significance and nature of the interdependences were used. A nonlinear dependence of RRIv vs. CORTv and of RRIv vs. RESPv was found. Both dependences seem to be unconnected with the functioning of both α1-adrenoceptor and cholinoceptor systems, but appear to be mediated by β-adrenoceptor mechanisms. A linear dependence of CORTv vs. RRIv and of RESPv vs. RRIv was also found. Both dependences seem to be unconnected with the operation of α1-adrenoceptor, β-adrenoceptor and cholinoceptor systems. It is suggested that both the cardiocortical and cardiorespiratory synchronizations studied seem to be mediated by β-adrenoceptor mechanisms.