Microcirculation Effects

Vopr Kurortol Fizioter Lech Fiz Kult. 2009 Sep-Oct;(5):9-11.

Rehabilitative medical technology for the correction of microcirculatory disorders in patients with arterial hypertension.

[Article in Russian]

Kul’chitskaia DB.

Abstract

The study with the use of laser Doppler flowmetry has revealed pathological changes in the microcirculatory system of patients with arterial hypertension. Their treatment with a low-frequency magnetic field showed that its effect on microcirculation depends on the regime and site of application of magnetotherapy as well as its combination with other physical factors. Frontal application of the magnetic field had the most pronounced beneficial effect on dynamic characteristics of microcirculation. Pulsed regime of magnetotherapy was more efficacious than conventional one. Amplipulse magnetotherapy produced better results than monotherapy.

Int J Sports Med. 2005 Dec;26(10):886-90.

The effects of low-dosed and high-dosed low-frequency electromagnetic fields on microcirculation and skin temperature in healthy subjects.

Schuhfried O, Vacariu G, Rochowanski H, Serek M, Fialka-Moser V.

Department of Physical Medicine and Rehabilitation, Medical University of Vienna, Allgemeines Krankenhaus, Waehringer Guertel 18-20, 1090 Vienna, Austria. othmar.schuhfried@univie.ac.at

Abstract

The purpose of this randomized double-blind cross-over study was to investigate whether a low-dosed pulsed low-frequency magnetic field or a high-dosed pulsed low-frequency magnetic field improves the cutaneous microcirculation and alters the temperature of the foot. Twelve healthy subjects (five women, seven men) aged on average 25.8 years participated in the trial. Based on a randomization list, one of the following three interventions was applied for 30 min through a cushion placed below the non-dominant foot: either a pulsed low-dosed magnetic field (100 uT, basic frequency 30 Hz with a frequency modulation) or a pulsed high-dosed magnetic field (8.4 mT, 10 Hz), or sham treatment. The individual treatment sessions were applied in intervals of one week, at the same time of the day. Cutaneous microcirculation (laser Doppler flowmetry) and temperature (infra-red thermovision) were measured in the dorsum of the foot and the great toe every 5 min during the intervention, and 5 and 10 min post-intervention. With both pulsed low-dosed magnetic field and pulsed high-dosed magnetic field, just as with the sham treatment, a minor drop in temperature and decrease in microcirculation took place. A two-way repeated-measures analysis of variance revealed no significant difference between the interventions for any parameter. It was concluded that a local application of a pulsed low-frequency magnetic field to the foot did not enhance temperature or cutaneous microcirculation in healthy subjects.

Microvasc Res. 2005 Jan;69(1-2):24-7.

Effects of a static magnetic field of either polarity on skin microcirculation.

Mayrovitz HN, Groseclose EE.

College of Medical Sciences, Nova Southeastern University, 3200 S. University Drive, Ft. Lauderdale, FL 33328, USA. mayrovit@nova.edu

Abstract

Our specific aim was to investigate whether a local static magnetic field of a permanent magnet, of either pole, affects resting skin blood perfusion. This was done by measuring skin blood perfusion (SBF) by laser-Doppler in dorsum skin of 2nd and 4th fingers of the nondominant hands of 12 volunteers. Both fingers were first exposed to sham magnets, and then the 2nd finger was exposed alternately to north and south poles of a neodymium magnet that produced a field of 4024 G at the palmar part of the finger and a field of 879 +/- 52 G at the site of finger dorsum SBF measurement. Each of the three exposure intervals was 15 min. SBF values were analyzed by first computing the average SBF during the last 5 min of each of the three 15-min exposure intervals. These SBF averages were initially tested for magnet or magnet-pole effects by analysis of variance for repeated measures with finger as a factor, using SBF values for each finger as the test variable. Results of this analysis revealed a large variability in finger SBF among subjects and no significant difference in SBF between exposure conditions (P = 0.705) or any significant interaction between SBF and finger (P = 0.396). However, when intersubject variability was reduced by using the flow difference between treated and nontreated fingers in each exposure interval as the test variable, a statistically significant effect (P = 0.016) attributable to magnet exposure was uncovered. This effect was a reduction in resting SBF in the magnet-exposed fingers that was similar for north and south pole magnet exposure. The present findings are the first to demonstrate a direct effect of locally applied magnets on human skin blood perfusion.

J Orthop Res. 2004 Jan;22(1):80-4.

Microcirculatory effects of pulsed electromagnetic fields.

Smith TL, Wong-Gibbons D, Maultsby J.

Department of Orthopaedic Surgery, Wake Forest University School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157-1070, USA.tsmith@wfubmc.edu

PURPOSE: Pulsed electromagnetic fields (PEMF) are used clinically to expedite healing of fracture non-unions, however, the mechanism of action by which PEMF stimulation is effective is unknown. The current study examined the acute effects of PEMF stimulation on arteriolar microvessel diameters in the rat cremaster muscle. The study hypothesis was that PEMF would increase arteriolar diameters, a potential mechanism involved in the healing process.

METHODS: Local PEMF stimulation/sham stimulation of 2 or 60 min duration was delivered to the cremaster muscle of anesthetized rats. Arteriolar diameters were measured before and after stimulation/sham stimulation using intravital microscopy. Systemic hemodynamics also were monitored during PEMF stimulation.

RESULTS: Local PEMF stimulation produced significant (p<0.001) vasodilation, compared to pre-stimulation values, in cremasteric arterioles in anesthetized rats (n=24). This dilation occurred after 2 min of stimulation (9% diameter increase) and after 1 h of stimulation (8.7% diameter increase). Rats receiving “sham” stimulation (n=15) demonstrated no statistically significant change in arteriolar diameter following either “sham” stimulation period. PEMF stimulation of the cremaster (n=4 rats) did not affect systemic arterial pressure or heart rate, nor was it associated with a change in tissue environmental temperature.

CONCLUSIONS: These results support the hypothesis that local application of a specific PEMF waveform can elicit significant arteriolar vasodilation. Systemic hemodynamics and environmental temperature could not account for the observed microvascular responses.

Neurosci Lett. 2002 Nov 22;333(2):136-40.

Vasodilitation of muscle microvessels induced by somatic afferent stimulation is mediated by calcitonin gene-related peptide release in the rat.

Loaiza LA, Yamaguchi S, Ito M, Ohshima N.

Department of Biomedical Engineering, Institute of Basic Medical Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba Science City, Ibaraki 305-8575, Japan.

In anesthesized rats, the effects of electrical stimulation (ES) to the saphenous nerve on the microcirculation of the gracilis muscle were assessed through the measurement of two different hemodynamic parameters: (a). the muscle blood flow (MBF) using a laser Doppler flowmeter; and (b). the changes in diameter of the muscle arterioles observed directly using an intravital microscope system. Ipsilateral ES (5 V, 20 Hz, for 30 s) produced increases in MBF and mean arterial pressure (47+/-10% and 18+/-5%) over the baseline, while no significant changes in MBF were observed in the contralateral muscle. Neither selective nor simultaneous alpha- and beta-adrenergic blockade altered the increases in MBF induced by ipsilateral ES. The arteriolar diameter was found to increase by 38.9+/-5% following ipsilateral ES. This response in diameter was abolished after the topical application of a calcitonin gene-related peptide receptor antagonist (CGRP(8-37)). Contralateral ES produced a decrease in arteriolar diameter by 26+/-14%. Thus, ipsilateral nerve ES produced vasodilative responses in the muscle accompanied by increases in MBF independently of the sympathetic activity. Furthermore, CGRP was found directly involved in the reflex neural regulation of the muscle microcirculation, which suggests the participation of an axon reflex mechanism.

J Orthop Res. 1992 Mar;10(2):256-62.

The effects of pulsed electromagnetic fields on blood vessel growth in the rabbit ear chamber.

Greenough CG.

Department of Orthopaedics, Middlesbrough General Hospital, Cleveland, U.K.

A double-blind, controlled trial of the effects of pulsed electromagnetic fields on capillary growth in the rabbit ear chamber in adult New Zealand white rabbits has been performed. Three waveforms have been investigated. The first, a pulse burst waveform, produced a significant increase in the rate of growth of the vascular tissue within the chamber, but had no effect on macroscopic tissue maturation. The second and third, two different single pulse waveforms, had, in contrast, no significant effect on the rate of vascular growth and only an effect on vessel characteristics, with increased maturation of vessels using the second waveform. It is concluded that some of the observed effects of pulsed electromagnetic fields on tissue healing may be mediated through a primary effect on vascular growth.

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