ABSTRACT
Male mice exposed to hyperbaric oxygen (HBO) at 4.5 ATA O2 exhibit a number of toxic symptoms including convulsions, diminished respiration and an acoustic reaction controlled by the central nervous system. To study whether stimulation of the nervous system could offer protection against the convulsions, mice were injected i.p. with various doses of d-amphetamine before HBO. At a dose of 1.0 mg X kg-1 of d-amphetamine the mice could stay at 5 ATA O2 without convulsions about three times as long as those injected with saline only. At high doses, 4 and 8 mg X kg-1, there was a weak protective effect or the time to convulsions was shortened. Amphetamine increases the release of dopamine in the brain and it is possible that the mechanisms of protection against HBO induced convulsions are involved in that process. The degree of protection, however, depends on the dose; therefore, it also is supposed that amphetamine in low doses acts on the autoreceptors with a presynaptic effect, which in this case is protective against the convulsions without affecting the respiration.
Subject(s)
Dextroamphetamine/therapeutic use , Hyperbaric Oxygenation/adverse effects , Seizures/therapy , Animals , Body Temperature/drug effects , Male , Mice , Mice, Inbred Strains , Respiration/drug effects , Seizures/etiologyABSTRACT
Male mice were irradiated with microwaves of 2450 MHz at a power intensity of 1, 10, and 100 mW/cm2 and a dose of 300 mW.min/cm2. An intensity of 100 mW/cm2 for 3 min causes thermal effects. The rectal temperature increased 2 degrees C, and the respiratory minute volume decreased during the first 2 min. After that, it increased rapidly and fluctuated until the irradiation was finished, when the minute volume decreased to a value lower than normal. A new method has been used for studying the effects on the nervous system with the help of tone pulses and the respiratory minute volume, an acoustic reaction. This reaction is affected at the very moment the irradiation starts and remains for some minutes after irradiation is finished. During an irradiation of 10 mW/cm2 in 30 min, both the minute volume and the acoustic reaction are decreased. The rectal temperature does not change. 1mW/cm2 during 300 min does not change the minute volume nor the rectal temperature but decreases the acoustic reaction 4 and 5 h after irradiation has started. In the present experiments, it is possible to evaluate the influence of heat and the heat regulation with the help of the respiratory minute volume and rectal temperature. The effects on the conditioned acoustic reaction indicate that the nervous system is involved independently of the created heat and the thermal regulatory processes during and after irradiation with microwaves of 2450 MHz and at intensities of 1, 10, and 100 mW/cm2.
Subject(s)
Microwaves/adverse effects , Respiration/radiation effects , Acoustic Stimulation , Animals , Body Temperature Regulation/radiation effects , Lung Volume Measurements , Male , Mice , Nervous System/radiation effects , SafetyABSTRACT
Anesthetized rabbits were exposed to blunt impact on the right chest wall. The controlled impact was delivered with a special machine equipped with a captive piston driven by a freely falling weight. Chest wall deflections were recorded in order to study the effects of magnitude and rate of deformation of the thorax on the resulting lung injury. The ranges of magnitude and rate of deformation corresponded to an inward deflection of the chest wall of about 5-60% of the lateral diameter of the chest, and to a velocity of the chest wall of about 2-20 m/s. Impulses delivered to the chest and intrathoracic pressures were also studied. Severe hemorrhages in the lungs were produced at velocities of the chest wall exceeding about 10 m/s. For velocities of the chest wall below about 5 m/s, lethal injuries were produced without severe hemorrhages in the lungs.
