Assessment of Intramural Blood Flow and Neurogenic Control in Intact and Hypertrophic Urinary Bladder with Harmonic Analysis of Bioimpedance in Rats

Abstract

High-resolution impedancometry and harmonic (Fourier) analysis of variable component of bioimpedance revealed rhythmic oscillations of urinary bladder bioimpedance at the Mayer wave, respiration, and heartbeat frequencies. The power values of the corresponding Mayer, respiratory, and cardiac peaks were calculated to assess circulation in the urinary bladder wall and its autonomic nervous control at various stages of infusion cystometry in intact rats and in the rats with preliminary formed infravesical obstruction (IVO). In intact rats, filling of the bladder with physiological saline diminished the power of the first (fundamental) cardiac peak attesting to a decrease of the blood flow in the bladder wall. Simultaneously, the power of low-frequency Mayer peak reflecting sympathetic activity increased, while the power of respiratory peak decreased supposedly reflecting abatement of the parasympathetic influences. Bladder voiding was accompanied by a decrease of Mayer peak and increase of the respiratory one. Prior to infusion cystometry, the intravesical pressure in IVO rats was elevated while the power of fundamental cardiac peak was below the control value. Filling the bladder in these rats was accompanied by further decrease of the cardiac peak reflecting still greater drop in blood supply. In control rats, voiding the bladder normalized the vesical circulation assessed by the cardiac peak, while in IVO rats this peak remained decreased. The reciprocal changes of Mayer and respiratory peaks observed during infusion cystometry in the norm were replaced by unidirectional decrease in the power of both peaks in IVO rats, which probably attest to disturbance of autonomic nervous control in the hypertrophic urinary bladder in these rats.

Electrical Rhythms Revealed by Harmonic Analysis of a High-Resolution Cardiogram

“…It is a common knowledge that the ohmic (bioimpedance) M-and R-waves emerge in various organs and relate to regional activity of sympathetic and parasympathetic ANS branches [1][2][3][4]6,15]. By assuming that ANS also trigger the myocardial voltaic M-, R-, and U-waves, heterogeneity of myocardial innervation [7] should be taken into consideration.…”

“…It is viewed that sympathetic and parasym- pathetic branches of ANS send the spikes to the heart at low (Mayer, 0.04-0.15 Hz) and high (respiration) frequencies, respectively [5,8,13]. New data expanded this view to the nervous control of circulation in skeletal muscles and the organs of urogenital system [1,2,6,15]. In this paradigm, it can be hypothesized that M-and R-waves in ECG refl ect, respectively, the levels of sympathetic and parasympathetic infl uences in the myocardium.…”

“…Taking into consideration the relation of regional bioimpedance oscillations to respiration [1][2][3][4]6,15], the measurements had been made in norm and under the action of myorelaxant succinylcholine chloride. By analogy to bioimpedance…”

“…New vistas opened up due to recording of high-resolution rheograms and the use of bioimpedance harmonic analysis, which made it possible to examine the spectrum of small bioimpedance variations at low frequencies corresponding to respiration and Mayer wave [3,4,15]. The spectral parameters had been employed to assess regional activity of autonomic nervous system (ANS) and regional circulation in patients with the diseases of urogenital system [1,2,6]. Currently, the pronounced potentiality of harmonic analysis in assessment of low-frequency electrical rhythms in living organism is beyond question, but it should be stressed that bioimpedance is only one of the electrical parameters of biological objects.…”

“…Taking into consideration the relation of regional bioimpedance oscillations to respiration [1][2][3][4]6,15], the measurements had been made in norm and under the action of myorelaxant succinylcholine chloride. By analogy to bioimpedance variations in various organs [4,15], we hoped to detect in ECG the refl ection of slow processes ongoing in the myocardium at respiration and Mayer frequencies and to disclose the fi ne structure of pulsatile harmonics.…”