Effect of the low-frequency impulse magnetic field on the autonomic nervous system in animals

The effect of weak (up to 3.5 mT) low-frequency (up to 100 Hz) impulse magnetic field on the state of the vegetative nervous system of animals has been studied by analyzing the variability of the heart rate. The effect of the magnetic field was estimated by a specially designed complex for recording cardiac signals of animals. Several specially selected regimes of impulse magnetic fields were studied. It was shown that the impulse magnetic field possesses a high biological activity at all regimes used, and the indices of the vegetative nervous system after the exposure to the impulse magnetic field approach the values typical for normotonic animals. This makes it possible to use magnetic fields at these regimes in magnetotherapy.     

Effect of a low-frequency magnetic field on systemic arterial pressure in spontaneously hypertensive rats

The effect of low-frequency magnetic field (MF) on systemic blood pressure has been studied in chronic experiments on 21 spontaneously hypertensive rats. The animals' kidney area was exposed to MF (induction value 30T). Direct blood pressure measurements have revealed an antihypertensive effect.     

Effect of juvenile hormone on the autonomic nervous system

The effects of juvenoids on the autonomic nervous system, which controls certain physiological functions by means of special extracardiac pulsations in hemolymph pressure, have been studied in pupae of the mealworm, Tenebrio molitor. Prolonged tensiometric monitoring of the hemolymph pressure changes revealed that the extra-pupal development that had been caused by juvenoids evoked unusual reappearance of prepupal pattern of extracardiac pulsations. By contrast, the specific pharate adult types of the pulsations completely disappeared. The functioning of the autonomic nervous system was aberrant or incomplete during an unsuccessful extra-pupal ecdysis. It is suggested that malfunction of the autonomic nervous system in the extra-pupal instars may be the reason for the ecdysial failures associated with the use of juvenoids.     

Effect of alternating the magnetic field on phosphate metabolism in the nervous system of Helix pomatia

The effect of extremely low frequency magnetic fields (50 Hz, 0.5 mT) - ELF-MF, on phosphate metabolism has been studied in the isolated ganglions of the garden snail Helix pomatia, after 7 and 16 days of snail exposure to ELF-MF. The influence of ELF-MF on the level of phosphate compounds and intracellular pH was monitored by 31P NMR spectroscopy. Furthermore, the activity of enzymes involved in phosphate turnover, total ATPases, Na+/K+-ATPase and acid phosphatase has been measured. The exposure of snails to the ELF-MF for the period of 7 days shifted intracellular pH toward more alkaline conditions, and increased the activity of investigated enzymes. Prolonged exposure to the ELF-MF for the period of 16 days caused a decrease of PCr and ATP levels and decreased enzyme activity, compared to the 7-day treatment group. Our results can be explained in terms of: 1. increase in phosphate turnover by exposure to the ELF-MF for the period of 7 days, and 2. adaptation of phosphate metabolism in the nervous system of snails to prolonged ELF-MF exposure.     

The autonomic nervous system regulates gastric ghrelin secretion in rats

Plasma ghrelin levels are responsive to short- and long-term nutrient fluctuation, but the mechanisms of its regulation are largely unknown. To explore the role of the autonomic nervous system in the regulation of ghrelin secretion, we measured plasma ghrelin levels after administration of cholinergic and adrenergic agents in rats under normally fed and 48-h fasting conditions. To assess the short- and long-term effects of vagotomy on ghrelin secretion, plasma ghrelin levels and stomach ghrelin levels and gene expressions were measured in rats subjected to fed or fasting. Additionally, we investigated whether plasma ghrelin levels were affected by the anorexigenic gastrointestinal peptides cholecystokinin and somatostatin. In the pharmacological study, plasma ghrelin levels were increased by a muscarinic agonist, an alpha-adrenergic antagonist, and a beta-adrenergic agonist, and decreased by a muscarinic antagonist and an alpha-adrenergic agonist. Vagotomy inhibited ghrelin secretion acutely, but promoted ghrelin release from the stomach at later time points. Stomach ghrelin mRNA levels were unchanged after fasting, but were significantly upregulated in vagotomized rats. The change of plasma ghrelin levels in nutrient fluctuation was independent of the endogenous effects of cholecystokinin and somatostatin. This study demonstrates that stomach ghrelin secretion is modulated by both the cholinergic and adrenergic arms of the autonomic nervous system. The dissociation between the short- and long-term effects of vagotomy on plasma ghrelin level indicates that an additional neural control mechanism might be involved in the regulation of ghrelin secretion.     

Role of the autonomic nervous system in cyclophosphamide-induced heart mitochondrial dysfunction in rats

This study was designed to clarify mechanisms responsible for cyclophosphamide-induced cardiotoxicity. Rats were divided into 2 groups: the cyclophosphamide group, which received cyclophosphamide (100 mg/kg) intraperitoneally once a day for 4 consecutive days; and the control group, which remained untreated. In each group, myocardial mitochondrial respiratory function, enzymic activities in the respiratory chain, and ventricular acetylcholine and norepinephrine concentrations were measured. In the cyclophosphamide group, decreases in mitochondrial respiratory function and in enzymic activities in the respiratory chain were observed compared with those of the control group. Administration with cyclophosphamide caused increases in acetylcholine and norepinephrine in the myocardium. As an increase in tissue acetylcholine level is reported to be linked with the genesis of myocardial damage, we conclude that cyclophosphamide-induced cardiotoxicity is closely related to mitochondrial dysfunction and that alterations in the autonomic nervous system might be related to this dysfunction.     

Effect of a low-frequency alternating magnetic field on the formation of avoidance reflexes in the rat

Alternating magnetic field with induction of 3 mTl, frequency of 10 Hz, homogenous, with impulses of sinusoidal form and a vector with horizontal direction, produces an inhibitory effect on the formation of avoidance reflexes in white rats. The after-effect of the field lasts less than 1 hour.     

Role of the autonomic nervous system in push-pull gravitational stress in anesthetized rats.

Tolerance to +G(z) stress is reduced by preceding exposure to -G(z) (push-pull effect). The mechanism(s) responsible for this effect are not fully understood, although the arterial baroreceptor reflexes have been implicated. We investigated the integrative response of the autonomic nervous system by studying responses to gravitational stress before and after autonomic function was inhibited by hexamethonium in 10 isoflurane-anesthetized male and female Sprague-Dawley rats. Animals were restrained supine and subjected to two rotations imposed about the x-axis: 1) a control G profile consisting of rotation from 0 G(z) (+1 G(y)) to 90 degrees head-up tilt (+1 G(z)) for 10 s and 2) a push-pull G profile consisting of rotation from 0 G(z) to 90 degrees head-down tilt (-1 G(z)) for 2 s immediately preceding 10 s of +1 G(z) stress. Eight G profiles consisting of equal numbers of control and push-pull trials were imposed by using a counterbalanced design. We found that hexamethonium lowered baseline arterial pressure and abolished the push-pull effect. The lack of a push-pull effect after autonomic blockade persisted when arterial pressure was restored to baseline levels by phenylephrine infusion. Lowering baseline arterial pressure by sodium nitroprusside infusion or by hemorrhage when autonomic function was intact also abolished the push-pull effect. We conclude that intact autonomic function and a normal baseline arterial pressure are needed for expression of the push-pull effect in anesthetized rats subjected to tilting.     

Effect of the autonomic nervous system on the resistance of heart ventricles to fibrillation

Effects of vagus stimulation and cutting on the tolerance of heart ventricles to fibrillation in cats have been studied. The parasympathetic effects increased the tolerance of heart ventricles to fibrillation while sympathetic ones--decreased it.     

Influence of extremely low-frequency magnetic field on the activity of antioxidant enzymes during skin wound healing in rats

The aim of this study was to evaluate the activity of the antioxidant enzymes mitochondrial and cytosolic superoxide dismutase (EC 1.15.1.1), glutathione peroxidase (POX, EC 1.11.1.9) and glutathione S-transferase (EC 3.1.2.7), as well as the concentration of malone dialdehyde (MDA), as an indicator of lipid peroxidation rate in the liver tissue homogenates and blood serum of male rats exposed to extremely low-frequency magnetic field (ELF-MF) in order to improve the healing process of an experimental cut wound on the back of each animal. The exposure to ELF-MF with frequency 40 Hz and magnetic flux density 10 mT induced an increase in POX serum activity and a decrease in MDA contents in the liver tissue, which suggests the inhibition of phospholipid peroxidation and subsequent stabilization of cellular membranes, as a result of ELF-MF action. Based on the results obtained, it seems that ELF-MF could be a useful supplement in the complex treatment of prolonged wound healing, due to the activation of endogenous enzymatic antioxidant system.