Static magnetic field blood pressure buffering, baroreflex vs. vascular blood pressure control mechanism

Abstract

Purpose: We compared the effect of static magnetic field (SMF) and verapamil, a potent vascular calcium channel blocking agent, on sudden elevation in blood pressure in conjunction with arterial baroreflex sensitivity (BRS) and microcirculation.

Materials and methods: Forty-four experiments were performed on conscious rabbits sedated using pentobarbital intravenous (i.v.) infusion (5 mg kg⁻¹ h⁻¹). Mean femoral artery blood pressure (MAP), heart rate, BRS and ear lobe skin microcirculatory blood flow, estimated using microphotoelectric plethysmography (MPPG), were simultaneously measured after a 40 min exposure of the sinocarotid baroreceptors to 350 mT SMF, generated by Nd₂-Fe₁₄-B magnets, or 30 min of verapamil i.v. administration (20 μg kg⁻¹ min⁻¹). BRS was assessed from heart rate and MAP responses to i.v. bolus of nitroprusside and phenylephrine.

Results: The decrease in phenylephrine-induced abrupt elevation in MAP (ΔMAP_AE) was significantly larger after verapamil than after SMF exposure. ΔMAP_AE inversely correlated with verapamil-induced significant increase in ΔMPPG (r = 0.53, p < 0.000) and with SMF-induced significant increase in ΔBRS (r = 0.47, p < 0.016).

Conclusions: Our results suggest that verapamil-potentiated vascular blood pressure buffering mechanism was more effective than SMF-potentiated baroreflex-mediated blood pressure buffering mechanism, and a potential benefit of both approaches in cardiovascular conditions with abrupt high elevation in blood pressure.

Keywords:

• baroreflex sensitivity
• heart rate variability
• blood pressure variability
• microcirculation
• verapamil
• calcium channel blocker

Acknowledgements

This research was carried out at the Department of Environmental Health in the National Institute of Public Health, Tokyo, Japan, under the auspices of the Japanese Government Research Awards for Foreign Specialists, administrated by the Science and Technology Agency of Japan.

Declaration of interest: The author reports no conflicts of interest. The author alone is responsible for the content and writing of the paper.