Carbonic anhydrase activity in the red blood cells of sea level and high altitude natives

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.

Increase in succinate dehydrogenase activity in mice brain during chronic hypoxia

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.