RESUMO
Blood flow in different organs, cardiac output, and arterial blood pressure were measured in unanesthetized rats under 1, 2, 3.5, 5, and 7 ATA O2, during first electrical discharge developed at 7 ATA O2 and following decompression. Brain, spinal cord, and hypophysis blood flow were reduced after 10 min of exposure to 2, 3.5, and 5 ATA O2 and were normal before and during first electrical discharge. Liver and muscle blood flow were significantly reduced under all investigated pressures, while myocardium, lung, kidney, and adrenal blood flow remained unchanged except for a significant increase in myocardium and lung blood flow under 1 ATA O2. Cardiac output was significantly decreased while arterial blood pressure was significantly decreased under all investigated pressures. The total peripheral resistance increased 36 to 81% at various oxygen pressures. These results are discussed in relation to the possible involvement of hemodynamic changes in awake animals, in the development of the adverse effects of HOP.
Assuntos
Pressão do Ar , Pressão Atmosférica , Hemodinâmica , Oxigênio , Glândulas Suprarrenais/irrigação sanguínea , Animais , Pressão Sanguínea , Débito Cardíaco , Circulação Cerebrovascular , Circulação Coronária , Oxigenoterapia Hiperbárica , Rim/irrigação sanguínea , Circulação Hepática , Masculino , Músculos/irrigação sanguínea , Hipófise/irrigação sanguínea , Circulação Pulmonar , Ratos , Fluxo Sanguíneo Regional , Medula Espinal/irrigação sanguínea , Resistência VascularRESUMO
The excitability of the cortex in adrenalectomized and normal adult male rats to High Oxygen Pressure (HOP) was studied 2, 3, 4, 6, 8, 12 and 22 d after bilateral adrenalectomy and implantation of cerebral electrodes. Continuous electroencephalographic (EEG) recordings were obtained until the appearance of the first paroxysmal electrical discharges, which was considered to be the first indicator of the toxic effects of hyperbaric oxygen. A statistically significant change in excitability of the cortex to oxygen toxicity from 2 to 22 d following adrenalectomy was shown. Comparison of the sensitivity of the normal and adrenalectomized rats to HOP 2 d after the operation showed significant resistance of adrenalectomized rats at this time. This resistance disappeared gradually, when compared with normal rats, and cortical susceptibility increased significantly 22 d after adrenalectomy. The possible disturbances responsible for the changes in excitability of the cortex to HOP in adrenalectomized rats are discussed.