Wavelet analysis of cerebral blood flow in terminal rats

Abstract

In the last decade, the attention of clinicians has focused on cerebral hypoperfusion, the range of ischemic cerebral blood flow from the lower border of autoregulation to the threshold of necrosis. The search for methods of studying the regulation of blood flow in hypoperfusion remains highly relevant.

Aim. To study regulatory influences on cerebral microvessels in the conditions of severe ischemia by laser Doppler flowmetry (LDF).

Materials and methods. The experiments were performed on 10 control and 10 experimental rats under anesthesia (chloral hydrate, 400 mg/kg, i/b). Cerebral blood flow (CBF) was recorded in the neocortex by LDF. Regulatory influences from the endothelium, nervous system, myocytes, respiratory excursions and pulse were studied by the wavelet analysis of LDF-grams.

Results. In the control with an average blood pressure (BP) of 84 [83; 86] mm Hg, the CBF was 27 [22, 32] p. u. In the experimental group, after a decrease in systemic BP to 30 [28; 31] mm Hg, the CBF was 6 [4, 7] p. u., which corresponded to severe ischemia. Absolute values of blood flow fluctuations significantly decreased in the myogenic (50%), respiratory (63%) and pulse (28.6%) ranges. Furthermore, the relative contributions of the endothelial and neurogenic ranges increased by 140% and 90%, respectively, which reflects the process of reducing the tone of cerebral vessels in the conditions of centralization of blood circulation.

Conclusion. The wavelet analysis of CBF reveals subtle features of its regulation by the mechanisms that form vascular tone.