Myogenic dynamics

Fig. 12.8 Phase plot illustrating the oscillation in the variables associated with the afferent arteriole. The dynamics is interpreted as a 2 8 synchronization between the slowTGF-mediated mode and the fast myogenic mode. T = 16 s and a = 24.2. This is the same solution that we referred to as a period-2 solution in connection with Fig. 12.5.

As demonstrated by the power spectra in Figs. 12.2a and 12.3b, regulation of the blood flow to the individual nephron involves several oscillatory modes. The two dominating time scales are associated with the period Tsiow 30—40 s of the slow TGF-mediated oscillations and the somewhat shorter time scale Tjast 5—10 s defined by the myogenic oscillations of the afferent arteriolar diameter. The two modes interact because they both involve activation of smooth muscle cells in the arteriolar wall. Our model describes these mechanisms and the coupling between the two modes, and it also reproduces the observed multi-mode dynamics. We can, therefore, use the model to examine some of the phenomena that can be expected to arise from the interaction between the two modes. 

The hmitations of the preparation are ) autocoid production and vascular reactivity may be altered in vitro, 2) the absence of flow dynamics may alter endothelial cell function, 3) the small amount of tissue limits biochemical measurements, 4) isolated arterioles do not exhibit myogenic responses to changes in transmural pressure. 

Regulation of CBF is a complex dynamical process and remains relatively constant over a wide range of perfusion pressure via a variety of feedback control mechanisms, such as metabolic, myogenic, and neurally mediated changes in cerebrovascular impedance respond to changes in perfusion pressure. The contribution to the overall CBF regulation by different areas of the brain is modeled by the statistics of the fractional derivative parameter, which determines the multifractal nature of the time series. The source of the multifractality is over and above that produced by the cardiovascular system. 

Borman, W.H., Urlakis, K.J. Yorde, D.E. (1994). Analysis of the in vivo myogenic status of chick somites by desmin expression in vitro. Dev. Dynamics, 199, 268-79. 

Juhas, M., Bursae, N., 2014. Roles of adherent myogenic cells and dynamic culture in engineered muscle function and maintenance of satellite cells. Biomaterials 35, 9438—9446. 

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