Background: Field stimulation of the carotid baroreceptors has been used successfully to induce long-term reduction in blood pressure. However, whether baroreceptor stimulation may affect the short-term blood pressure regulation function of the baroreceptors in normotensive and hypertensive conditions is not well established. Aim: To determine the effect of field stimulation of carotid baroreceptors on blood pressure in normotensive and hypertensive rats. Methods: Male Wistar Kyoto (WKY, n=7) and spontaneously hypertensive rats (SHR, n=7), each 15–19 weeks old, were anesthetized (urethane, 1.3 g/kg) and unilaterally vagotomized. Thoracic and aortic pressure was measured by an intravascular dual catheter tip pressure sensor (Science, 1.6F). Vessel stiffness was quantified by the pulse wave velocity (PWV) between the two pressure sensors. The left carotid artery was exposed and electrical field stimulation was applied to baroreceptors in the proximity of the carotid bifurcation (stimulation frequency 100 Hz, pulse width 0.53 ms, signal amplitude 3–5 v). A bolus of phenylephrine (1.5 μg) was delivered during baseline conditions (no stimulation) and during carotid baroreceptor stimulation to characterize baroreceptor function. Baroreceptor gain was computed as the absolute change in heart rate (HR) with respect to change in mean blood pressure (MAP). Results: Stimulation caused a significant reduction in HR and MAP in both WKY (P=0.034 for HR, P=0.02 for MAP) and SHR (P=0.0007 for HR, P=0.002 for MAP), indicative of sympathetic inhibition. Field stimulation of the carotid baroreceptors did not affect the baroreceptor gain in either group. WKY: gain at baseline (no stimulation), 0.7±0.19 bpm/mm Hg; gain during stimulation, 0.6±0.12 bpm/mm Hg. SHR: gain at baseline (no stimulation), 0.36±0.10 bpm/mm Hg; gain during stimulation, 0.44±0.12 bpm/mm Hg. There was a nonsignificant trend for reduction in gain in SHR compared to WKY in both baseline and stimulation conditions. PVW did not change significantly with stimulation in both WKY and SHR. Conclusions: Baroreceptor function was preserved during field stimulation of carotid baroreceptors in both WKY and SHR. This provides support for the use of field stimulation of baroreceptors as a means of blood pressure lowering therapy, whereby the acute and transient control of blood pressure in daily life is maintained.
|Number of pages||1|
|Publication status||Published - May 2015|
|Event||Annual Scientific Meeting of the High Blood Pressure Research Council of Australia (36th : 2014) - Adelaide, Australia|
Duration: 26 Nov 2014 → 28 Nov 2014