Dantrolene blocks the tonic contractions to carbachol and histamine with smaller effects on the phasic due to release of intracellular Ca2+ in ileal longitudinal muscle

Childhood exposure to manganese and postural instability in children living near a ferromanganese refinery in Southeastern Ohio

Airborne manganese (Mn) exposure can result in neurotoxicity and postural instability in occupationally exposed workers, yet few studies have explored the association ambient exposure to Mn in children and postural stability. The goal of this study was to determine the association between Mn and lead (Pb) exposure, as measured by blood Pb, blood and hair Mn and time weighted distance (TWD) from a ferromanganese refinery, and postural stability in children. A subset of children ages 7-9 years enrolled in the Marietta Community Actively Researching Exposure Study (CARES) were invited to participate. Postural balance was conducted on 55 children residing in Marietta, Ohio and the surrounding area. Samples of blood were collected and analyzed for Mn and Pb, and samples of hair were analyzed for Mn. Neuromotor performance was assessed using postural balance testing with a computer force platform system. Pearson correlations were calculated to identify key covariates. Associations between postural balance testing conditions and Mn and Pb exposure were estimated with linear regression analyses adjusting for gender, age, parent IQ, and parent age. Mean blood Mn was 10 μg/L (SEM=0.36), mean blood Pb was 0.85 μg/dL (SEM=0.05), and mean hair Mn was 0.76 μg/g (SEM=0.16). Mean residential distance from the refinery was 11.5 km (SEM=0.46). All three measures of Mn exposure were significantly associated with poor postural balance. In addition, low-level blood Pb was also negatively associated with balance outcomes. We conclude that Mn exposure and low-level blood Pb are significantly associated with poor postural balance.

Prevention of acute adriamycin cardiotoxicity by dantrolene in rats

Possible preventive effect of dantrolene against the peroxidative damage in rat heart which was induced by the administration of an acute dose of adriamycin (ADR, 20 mg/kg, i.p.) has been examined. Forty-eight hours after ADR administration, biochemical changes including the activities of serum creatine kinase isoenzyme (CK-MB), lactate dehydrogenase (LDH) and aspartate aminotransferase (AST) and the levels of malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in heart tissue were measured. Pretreatment of rats with dantrolene, given i.p. 30 min prior to ADR injection, substantially reduced the peroxidative damage in the myocardium, and markedly lowered the serum CK-MB, LDH and AST. The protective effects obtained by dantrolene administration, however, were not complete and did not reach those of the control group. Dantrolene, at 5 mg/kg, was useful to obtain significant protective effects, while the protector effect of higher dantrolene dosing level (10 mg/kg) was weak or absent. These results suggest that, at least in part, due to antioxidative properties, dantrolene may provide a significant protective effect against acute ADR-induced cardiotoxicity.

In vitro effects of dantrolene sodium and verapamil on noradrenaline-induced contractions of rabbit aorta and their interactions

The effects of dantrolene sodium (0.1 to 10 microM) and verapamil (0.01 to 1 microM) administered alone or together (1 microM verapamil, 0.1 to 10 microM dantrolene sodium) were investigated in isolated rabbit thoracic aorta precontracted with 0.1 microM noradrenaline (NA). Verapamil plus dantrolene sodium produced a dose-dependent inhibition of aortic strips contractions evoked by NA, and all concentrations of dantrolene sodium significantly decreased the inhibitory effect of 1 microM verapamil (p < 0.001, ANOVA). In conclusion, dantrolene sodium and verapamil inhibited 0.1 microM noradrenaline-evoked aorta contractions, and all doses of dantrolene sodium decreased the inhibitory effect of 1 microM verapamil in a dose-dependent manner.

Dantrolene protects erythrocytes against oxidative stress during whole-body irradiation in rats

In our study, we examined the radioprotective effects of dantrolene against gamma irradiation-induced damage of blood cells after total body irradiation of rats. Rats were divided into three groups of eight rats each. The first group was the control group receiving no dantrolene or irradiation, the second group received total body irradiation (RT) with 5 Gy of gamma irradiation only, and the third group received dantrolene at a dose of 5 mg x kg(-1) plus RT. Dantrolene was given intraperitoneally 30 min before RT. All groups were sacrificed 2 h after RT, and blood samples were taken. Leukocyte, and thrombocyte counts and hemoglobin levels were measured. Furthermore, malondialdehyde (MDA) levels in plasma and erythrocytes and superoxide dismutase (SOD) and glutathione peroxidase activities (GSH-Px) in erythrocytes were determined. It was found that pretreatment with dantrolene at a dose of 5 mg x kg(-1) significantly reduced the MDA levels and increased the antioxidant SOD and GSH-Px activities, and prevented the decrease in leukocyte and thrombocyte counts. We conclude that dantrolene has clear antioxidant properties when given prior to radiation exposure and the protective effect of dantrolene against damage inflicted by radiation, depends, at least in part, on the decrease in lipid peroxidation and increase in the activity of antioxidant enzymes SOD and GSH-Px.

Anti-inflammatory and antinociceptive properties of dantrolene sodium in rats and mice

Our study aimed at examining the possible anti-inflammatory and antinociceptive effects of dantrolene sodium in rats and mice. The anti-inflammatory effect of dantrolene sodium (2.5, 5 and 10 mg kg (-1)) was investigated and compared with diclofenac sodium (5 mg kg (-1)) using the formalin-, histamine-, and carrageenan-induced paw oedema and cotton pellet granuloma tests. Analgesic effects of dantrolene sodium were evaluated and compared with metamizol (200 mg kg (-1)) in acetic acid-induced writhing and formalin-induced paw licking tests. It was found that dantrolene sodium significantly diminished the nociceptive response in mice, showing at the same time considerable anti-inflammatory properties in rats.

Mechanism of the beneficial effects of dantrolene sodium on ethanol-induced acute gastric mucosal injury in rats

In our study, we examined anti-ulcerogen and antioxidant effects of dantrolene sodium on ethanol-induced gastric lesions in rats. Dantrolene sodium was administered intraperitoneally (i.p.) in several doses, and famotidine was used at a dose of 20 mg kg (-1). It was found that pretreatment with dantrolene sodium at doses of 1, 5 and 10 mg kg(-1) significantly reduced ethanol-induced gastric damage and malondialdehyde levels, and significantly increased antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities. We conclude that dantrolene sodium clearly has antioxidant properties and that the protective effect of dantrolene sodium against ethanol-induced gastric mucosal lesion, at least in part, depends upon the reduction in the lipid peroxidation and an increase in the activity of antioxidant enzymes SOD and GSH-Px.

In vitro antioxidant properties of dantrolene sodium

Dantrolene sodium is a skeletal muscle relaxant, which inhibits intracellular Ca2+ release from the sarcoplasmic reticulum. The aim of this study is to examine possible in vitro antioxidant effects of dantrolene sodium. For this reason, the in vitro antioxidant effects of dantrolene sodium were studied using thiocyanate methods. Additionally, the reducing power and free radical scavenging activity were determined. Dantrolene sodium showed strong antioxidant activity in the linoleic acid emulsion system. The antioxidant activity increased with an increasing amount of dantrolene sodium (50, 100, 250 microg). The 50, 100 and 250 microg samples of dantrolene sodium showed 55%, 70% and 82% inhibition on peroxidation of linoleic acid, respectively. On the other hand, the 250 microg sample of alpha-tocopherol showed 62% inhibition of peroxidation of linoleic acid. Like antioxidant activity, the reducing power of dantrolene sodium increased in a dose-dependent manner. The reducing power of dantrolene was statistically significant vs control, but lower than butylated hydroxytoluene (BHT) and quercetin. Although dantrolene sodium had free radical scavenging activity this was not statistically significant. In contrast to dantrolene sodium, quercetin and butylated hydroxyanisole (BHA) had highly potent free radical scavenging activities and those were statistically significant. According to the these results, it may be said that antioxidant effect of dantrolene sodium is more related to its antioxidant activity in linoleic acid emulsion and reducing power, than to its free radical scavenging activity. These properties may be major reasons for the inhibition of lipid peroxidation.

Dantrolene blocks the tonic contraction and calcium influx evoked by K+ in ileal longitudinal smooth muscle

1. Dantrolene (10(-5)-10(-4) M) reduced the K+ (60 mM) tonic response in accordance with decreased Ca2+ uptake, as determined by La method, more than the phasic in ileal muscle. 2. After saponin-treatment of the fibers, which leaves the Ca2+ storage sites intact, dantrolene had only a slight effect on the caffeine-induced contraction. In Triton-X-100-treated fibers, in which the Ca2+ release sites are destroyed, dantrolene did not affect the Ca(2+)-induced contraction. 3. The results suggest that dantrolene inhibited the high-K(+)-induced tonic response mainly by inhibiting Ca2+ influx via voltage-dependent Ca2+ channels in ileum without affecting contractile elements. In contrast, dantrolene had only a slight effect on the intracellular Ca2+ release from caffeine-sensitive release sites.