Mathematical relationships and their consequences between rat pulse waveform parameters and blood pressure during decreasing NO bioavailability

Information obtained from arterial pulse waveform (APW) is useful for characterization of cardiovascular system in particular (patho)physiological conditions. Our goal was to find out, if the relationship between rat APW parameters could be described by simple mathematical functions and find mathematical parameters for conditions of hypertension resulted from decreased NO bioavailability. Therefore, we explored details of 14 left carotid APW parameters of anesthetized male Wistar rats and mathematically characterized their relationship to systolic and diastolic blood pressure (BP) in the condition of gradual decrease of NO bioavailability after administration of L-NAME. The right jugular vein of anesthetized Wistar rats was cannulated for L-NAME administration. The left carotid artery was cannulated to detect arterial pulse waveform at high resolution. Here we show the time-dependent parallel changes of 14 APW parameters before and after i.v. administration of L-NAME and present mathematical functions that approximate the relationships of 12 APW parameters to systolic and diastolic BP. Some APW parameters had minor (e.g. heart rate) or biphasic (e.g. relative level of dP/dt_min) dependence on BP, but all relationships, within particular range of BP, could be approximated by known regression functions, as linear line (e.g. pulse BP), exponential decay (e.g. relative level of dP/dt_max), exponential growth (systolic area), exponential rise to maximum (relative augmentation index) or sigmoid function (e.g. increase of relative level dP/dt_min). The mathematical functions may assign APW parameters to decreased NO bioavailability. This may have predictive or diagnostic value.

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