Analysis and neuronal modeling of the nonlinear characteristics of a localcardiac reflex in the rat

Previous experimental results have suggested the existence of a local cardi ac reflex in the rat. In this study, the putative role of such a local refl ex in cardiovascular regulation is quantitatively analyzed. A model for the local reflex is developed from anatomical experimental results and physiol ogical data in the literature. Using this model, a systems-level analysis i s conducted. Simulation results indicate that the neuromodulatory mechanism of the local reflex attenuates the nonlinearity of the relationship betwee n cardiac vagal drive and arterial pressure. This behavior is characterized through coherence analysis. Furthermore, the modulation of phase-related c haracteristics of the cardiovascular system is suggested as a plausible mec hanism for the nonlinear attenuation. Based on these results, it is plausib le that the functional role of the local reflex is highly robust nonlinear compensation at the heart, which results in less complex dynamics in other parts of the reflex.