|M.Sc Student||Ertracht Offir|
|Subject||Survival in Confined Atmosphere|
|Department||Department of Medicine||Supervisors||Professor Noam Gavriely|
|Dr. Ran Arieli|
Hypoxia develops in confined atmospheres, such as sealed rooms, and sunken submarines. Survival in these conditions depends on O2 consumption, volume of the enclosed space, and temperature. Previous studies tested the effect of ambient conditions on survival in confined atmospheres, i.e., terminal inspired O2 pressure (PIO2t) and survival time. The present study tested the effect of two pharmaceuticals in swine: 1) Selegiline, an excitotoxicity protector (n=6); 2) Bosentan, an endothelin receptor antagonist, which inhibits hypoxic pulmonary vasoconstriction (n=5). The control group consisted of eight pigs. On the day preceding the experiment, each 30-kg immature pig was implanted with EEG and ECG electrodes, a thermistor located close to the carotid artery and cannulae to the carotid and pulmonary arteries and jugular vein. On the experimental day the animal was placed in the a sealed chamber while consuming oxygen. Physiological data were monitored until death. The action of Selegiline given in normoxia was tested by its effect on monoamino-oxidase B activity in brain samples. The efficiency of Bosentan given at a PIO2 of 60 torr was tested by its effect on the pulmonary circulation. Developing hypoxia changed physiological parameters in all groups, although the PIO2t weren’t different: 35±11, 37±3 and 30±5 torr for control, Bosentan and Selegiline, respectively. Selegiline failed to reduce PIO2t or extend survival and its sympathomimetic effect induced elevation of breathing frequency and CO2 output. In the Bosentan group, survival time increased and pulmonary vascular resistance was lowered, but hemoglobin levels were elevated, and stroke volume, pulmonary and systemic vascular resistance were reduced, probably due to pre-experimental lung inflammation and subsequent hypoxic acclimation This study documents physiological changes during developing hypoxia. Failure to prolong survival by pharmacological protection of these two critical systems warrants a similar investigation of the cardiovascular system.