MPE Values Research Articles

Title: Development of national safety regulations for medical use of lasers in the Netherlands

Until now there are no national safety regulations for the medical use of lasers in the Netherlands. However, a committee of experts from hospitals, Health Council of the Netherlands, TNO Medical Technology Unit and industry is preparing recommendations. Their work is based on MPE values and special measurements that are performed to assess divergence and intensity distribution of laser beams, as well as optical and thermal properties of materials that are used in the clinical setting. The final intention of the committee is to advise government and hospitals on technical, environmental and administrative measures for the safety of the various medical laser applications.

GABA-induced hypothermia in rats: Involvement of serotonergic and cholinergic mechanisms

1. 1. The effects of γ-aminobutyric acid (GABA) on body temperature of restrained rats has been studied. 2. 2. GABA (250–1000 mg/kg i.p.) caused a dose-dependent fall in BT of restrained rats at an ambient temperature of 18–22°C. 3. 3. The GABA-induced hypothermic response was attenuated by pretreatment with hexamethonium, p-chlorophenylalanine, methysergide, neostigmine and atropine (% MPE values: 27, 35, 51, 64 and 72 respectively). 4. 4. Pretreatment with methysergide and atropine was more potent than hexanmethonium and methysergide in inhibiting the GABA-induced hypothermia (% MPE = 68 and 47 respectively). 5. 5. The antagonism by neostigmine of GABA-induced hypothermia was attenuated by pretreatment with hexamethonium (7.5 mg/kg). 6. 6. Yohimbine and chlorimipramine potentiated GABA hypothermia (% MPE = −82 and −8 respectively). 7. 7. The data indicate that GABA-induced hypothermia may be mediated by serotonin and acetylcholine release. Muscarinic receptors may play an important role in the effect of GABA. The results support the hypothesis that the hypothermia induced by GABA is modulated by nicotinic receptors.