ISSN 0869-6632 (Print)
ISSN 2542-1905 (Online)


Synchronization of oscillations in the dynamics of ensembles of surface nephrons

Based on the analysis of experimental data we study the collective dynamics of ensembles from several tens nephrons located on a kidney surface. Using wavelet-analysis, the phenomenon of locking of instantaneous frequencies and phases is studied that is caused by the tubulo-glomerular feedback. It is shown that structural units of the kidney related to distinct nephron trees participate in clusters formation. The entrainment of frequencies and phases of oscillations for large groups of nephrons occurs only for some fragments of experimental data.

Method of empirical modes and wavelet­filtering: application in geophysical problems

Theoretical bases of empirical mode decomposition being one of the new methods of time-frequency analysis of processes with time-varying characteristics are discussed. It is shown that application of this approach together with wavelet-filtering allows one to study in details the structure of multicomponent registered signals recorded in prospecting seismology.

Time­frequency analysis of nonstationary processes: concepts of wavelets and empirical modes

A comparation of wavelets and empirical modes concepts is performed that represent the most perspective tools to study the structure of nonstationary multimode processes. Their advantages over the classical methods for time series analysis and restrictions of both approaches are discussed that needs to be known for correct interpretation of the obtained results. New possibilities in the study of signals structure at the presence of noise are illuctrated for digital single-channel experimental data of prospecting seismology.

Rhythmic processes of renal blood flow autoregulation and their interaction in the form of modulation of oscillations

Renal blood flow autoregulation at the level of individual nephrons includes two interacting mechanisms that produce oscillations with different time scales: the tubologlomerular feedback (TGF) and the myogenic response. Based on the wavelet-analysis of experimental data, we study in this work phenomena of amplitude and frequency modulation of myogenic oscillations by the TGF-rhythm. Features of nonlinear dependencies of amplitude and frequency deviation of modulated process versus the amplitude of modulating oscillations are revealed.

Dynamics of small groups of interacting nephrons in normal and renal hypertension states

Based on the wavelet-analysis of experimental data, we study in this paper the phenomenon of synchronization of oscillations in the dynamics of small groups of structural units of the kidney (paired nephrons and triplets). Distinctions between synchronous dynamics of interacting nephrons in normal and hypertensive rats are discussed. We show that mean duration of synchronous oscillations is about 3 times less in hypertensive rats.