RESUMO
BACKGROUND: Thirty-nine percent of permanent altitude dwellers in the Andes experience acral paresthesias. METHODS: Clinical examinations, sural nerve biopsies, and electrodiagnostic studies on peripheral nerves were performed on 15 men. Ten Cerro de Pasco (CP) natives living at 4,338 meters were biopsied. Three of these subjects had no burning feet/burning hands (BF/BH); three had BF/BH; and four had chronic mountain sickness (CMS), a maladaptation syndrome resulting from living in the Andes, all with BF/BH. Three patients with CMS were biopsied in Lima within hours after leaving CP. Two normal Lima natives were biopsied in Lima. Symptom scores for BF/BH and CMS score ratings were used. The nerves were assayed for Na+, K+ adenosine triphosphatase (ATPase), cytochrome oxidase (CO), substance P (SP), and endothelin (ET). RESULTS: Low ATPase was inversely related to symptom scores and CMS scores (p < 0.001). Patients with CMS biopsied in normoxia (Lima) had ATPase levels similar to those of controls. Nerve motor conduction velocities and sensory action potentials were normal. CO was inversely related to age (p < 0.03) and no relation of SP to any variable was found. ET levels were lower in sea level natives (p = 0.04). CONCLUSIONS: Acral paresthesias are associated with low ATPase in peripheral nerves. Lower ET levels of sea level natives likely reflect lowered release from vasa nervorum.
Assuntos
Altitude , Parestesia/fisiopatologia , Adulto , Doença da Altitude/enzimologia , Doença da Altitude/metabolismo , Biópsia , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Endotelinas/metabolismo , Humanos , Masculino , Condução Nervosa/fisiologia , Parestesia/enzimologia , Parestesia/metabolismo , Peru , ATPase Trocadora de Sódio-Potássio/metabolismo , Substância P/metabolismo , Nervo Sural/química , Nervo Sural/metabolismo , Nervo Sural/fisiopatologiaRESUMO
We measured the activities of Na(+)K(+) ATPase and of enzymes of the glycolytic pathway, Krebs cycle, and the respiratory chain in cerebral cortex of mice exposed to chronic hypoxia for three weeks and compared their values with those of sea level controls. There were no differences in Na(+)K(+) ATPase activity or in the activity of glycolytic enzymes. In the Krebs cycle, a 66% increase of succinate dehydrogenase activity was found due to a lower Km. In contrast, respiratory chain cytochrome oxidase activity was reduced by 12% in mice exposed to hypoxia. This suggested that the metabolic demand would be satisfied despite the respiratory chain depression (cytochrome oxidase), probably due to anaerobic energy production within the mitochondria (succinate dehydrogenase).
Assuntos
Córtex Cerebral/metabolismo , Metabolismo Energético/fisiologia , Hipóxia Encefálica/metabolismo , Animais , Doença Crônica , Ciclo do Ácido Cítrico , Transporte de Elétrons , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Masculino , Camundongos , Mitocôndrias/enzimologia , ATPase Trocadora de Sódio-Potássio/metabolismo , Succinato Desidrogenase/metabolismoRESUMO
Red blood cell carbonic anhydrase (CA) activity has not been studied in high altitude natives. Because CA is an intraerythocytic enzyme and high altitude natives are polycythemic, it is important to know if the activity of CA per red cell volume is different from that of their sea level counterparts. Blood was collected from healthy subjects living in Lima (150m) and from twelve subjects from Cerro de Pasco (4330m), and hematocrit and carbonic anhydrase activity were measured. As expected, the high altitude natives had significantly higher hematocrits than the sea level controls (p = 0.0002). No difference in the CA activity per milliliter of red cells was found between the two populations. There was no correlation between the hematocrit and CA activity.
Assuntos
Altitude , Anidrases Carbônicas/sangue , Eritrócitos/enzimologia , Anidrases Carbônicas/metabolismo , Hematócrito , Humanos , Pessoa de Meia-IdadeRESUMO
Red blood cell carbonic anhydrase (CA) activity has not been studied in high altitude natives. Because CA is an intraerythocytic enzyme and high altitude natives are polycythemic, it is important to know if the activity of CA per red cell volume is different from that of their sea level counterparts. Blood was collected from healthy subjects living in Lima (150m) and from twelve subjects from Cerro de Pasco (4330m), and hematocrit and carbonic anhydrase activity were measured. As expected, the high altitude natives had significantly higher hematocrits than the sea level controls (p = 0.0002). No difference in the CA activity per milliliter of red cells was found between the two populations. There was no correlation between the hematocrit and CA activity.
Assuntos
Humanos , Pessoa de Meia-Idade , Altitude , Anidrases Carbônicas/sangue , Eritrócitos , Eritrócitos/enzimologia , Anidrases Carbônicas/metabolismo , HematócritoRESUMO
Se midió la actividad de la succinato deshidrogenasa (SDH) en siete regiones cerebrales de ratones expuestos a tres semanas de hipoxia hipobárica (450 torr, 4380 metros por encima del nivel del mar), y se comparó con los controles normóxicos de nivel del mar. En el grupo hipóxico se encontró un aumento del 40 por ciento en la actividad de la SDH en la corteza y el hipocampo. Este podría ser un mecanismo compensatorio frente a la disminución de la actividad de otros componentes de la cadena respiratoria en condiciones de hipoxia hipobárica, como una estrategia para mantener la producción normal de ATP.