[PP.23.01] EFFECT OF UNILATERAL FIELD STIMULATION OF CAROTID BARORECEPTORS ON HEMODYNAMIC PROPERTIES IN RATS ON HIGH SALT DIET

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Abstract

Objective:

Electric field stimulation of carotid baroreceptors has been applied to treat patients with resistant hypertension caused by a range of conditions including high salt diet. This study investigated the effects of unilateral field stimulation of carotid baroreceptors on vascular stiffness and aortic wave reflection properties in Sprague-Dawley rats on high salt diet (HS) compared to age-matched controls (C).

Design and method:

Sprague-Dawley rats were fed with high salt (8% sodium chloride, n = 6) or normal chow (0.26% sodium chloride, n = 6) from weaning, with tail-cuff systolic blood pressure (SBP) was measured. Rats were anaesthetised (14 -17 weeks) and implemented with a field stimulation electrode surrounding the left carotid artery, immediately proximal to the bifurcation. Thoracic and abdominal aortic pressure and aortic flow were measured. Mean arterial pressure (MAP), mean aortic flow (MQ), heart rate (HR), pressure-dependant aortic pulse wave velocity (aPWV) and aortic resistance (aR) were calculated. Impedance analysis was applied using Fourier components of pressure and flow waveforms from which characteristic impedance (Zc), forward (Pf) and backward pressure (Pb) waveforms, reflection magnitude (Rm) and phase of zero crossing frequency (fzero) were calculated.

Results:

Tail-cuff SBP was greater in HS rats (125 ± 12 mmHg, control 117 ± 13 mmHg, p < 0.05). Stimulation caused a significant reduction in MAP, HR and aPWV in each group. However, that reduction was not significant between HS and control groups (Table). Results of other parameters are reported in the Table.

Conclusions:

The effect of field stimulation on aortic hemodynamic parameters in rats on high salt diet with altered blood pressure is comparable to that in control rats. Findings suggest that high salt diet does not influence hemodynamic effects of baroreceptor activation by field stimulation.

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