Fractal dynamics and synchronization of rhythms in urodynamics of female Wistar rats

Two phenomena are ubiquitous in physiological signals. First, they have temporal fractal structure. Secondly, they are rhythmic but with fluctuations. The fractal structure and rhythms can alter from normal to abnormal with disease or injury. Here, we demonstrate that a temporal "coherent" fractal structure and synchronization of rhythms are two essential features for concerted systemic functions in urodynamics of female Wistar rats. We report evidence on the dynamic interaction in the micturition reflex of lower urinary tract: the rhythms of detrusor of the bladder and external urethral sphincter are synchronized around 7 Hz and their fractal dimensions as functions of time are temporally "coherent" under 1.5 during voiding in order to facilitate the concerted process. On the other hand, in the spinal cord injured rats, either the temporal coherent structure of fractal or the underlying synchronization of rhythms is impaired, weakened, or absent. These results have potential implications in the diagnosis of the so-called "dynamical" diseases. (C) 2004 Elsevier B.V. All rights reserved.