MODULATION OF CARDIOVASCULAR CONTROL MECHANISMS AND THEIR INTERACTION

It is generally held that the role of a specific control element can o nly be understood within its physiological environment. The reviewed s tudies make it clear that there is a potent interplay between locally produced substances such as adenosine, nitric oxide, prostaglandins, a nd various others all interacting with the central level of control. T his can occur at central sites (e.g., nitric oxide in the brain) or in the periphery (e.g., neural influence on autoregulation). The interac tions are more or less pronounced during specific physiological challe nges. Furthermore, several of these interactions are altered under pat hological circumstances, and in some cases, these interactions seem to maintain or even augment the severity of disease, When more than thre e parameters participate in an interaction, the resulting regulation m ay become extremely complex. If these parameters are nonlinearly coupl ed with each other, the only way to shed light onto the nature of cont rol network is by treating it as a black box. With the use of spectral analysis or nonlinear methods, it is possible to disentangle the fund amental nature of the system in terms of the complexity and stability. Therefore, modern developments in cardiovascular physiology utilizing these techniques, some of which are derived from the ''chaos theory,' ' are reviewed.