Static magnetic field effect on microcirculation, direct versus baroreflex-mediated approach

Abstract

We compared in conscious rabbits, sedated using pentobarbital intravenous (i.v.) infusion (5 mg kg^{− 1} h^{− 1}), the effect of a static magnetic field (SMF), generated by Nd₂–Fe₁₄–B magnets, on microcirculation during its 40 min local exposure to the microvascular network in cutaneous tissue [20 sham exposure and 20 SMF (0.25 T) exposure runs] or to sinocarotid baroreceptors [14 sham exposure and 14 SMF (0.35 T) exposure runs]. Mean femoral artery blood pressure (BP), heart rate (HR), arterial baroreflex sensitivity (BRS), assessed from HR and BP responses to i.v. bolus of nitroprusside and phenylephrine, and microcirculatory blood flow, using microphotoelectric plethysmography (MPPG), were simultaneously monitored. SMF significantly increased microcirculation on a 17.8% in microvascular and on a 23.3% in baroreceptor exposure series. In baroreceptor exposure series, SMF significantly decreased BP, increased heart rate variability, BRS and sodium nitroprusside (NO-donor) i.v. bolus microcirculatory vasodilatory effect. These suggest augmentation of the arterial baroreflex capacity support NO-dependent vasodilation, by increased sensitivity of vessels to NO, to be a new physiological mechanism of BP buffering and microcirculatory control. A significant positive correlation was also found between increase in BRS and in MPPG (r = 0.66, p < 0.009), indicating baroreflex participation in the regulation of the microcirculation and its enhancement after SMF exposure. Both direct and baroreflex-mediated approaches demonstrate SMF significant vasodilatory effect with potential clinical implication in macro- and microcirculatory disorders.

Keywords::

• baroreflex sensitivity
• heart rate variability
• blood pressure variability
• NO-dependent vasodilation
• endothelium-derived hyperpolarizing factor

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.