Evolving in thin air—Lessons from the llama fetus in the altiplanoReportar como inadecuado




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Resumen

Compared with lowland species, fetal life for mammalian species whose mothers live in high altitude is demanding. For instance, fetal llamas haveto cope with the lowfetal arterial PO2 of all species, but also the likely superimposition of hypoxia as a result of the decreased oxygen environment inwhich the mother lives in the Andean altiplano. When subjected to acute hypoxia the llama fetus responds with an intense peripheral vasoconstrictionmediated by alpha-adrenergic mechanisms plus high plasma concentrations of catecholamines and neuropeptide Y NPY. Endothelial factors suchas NO and endothelin-1 also play a role in the regulation of local blood flows. Unlike fetuses of lowland species such as the sheep, the llama fetusshows a profound cerebral hypometabolic response to hypoxia, decreasing cerebral oxygen consumption, Na–K-ATPase activity and temperature,and resulting in an absence of seizures and apoptosis in neural cells. These strategies may have evolved to prevent hypoxic injury to the brain orother organs in the face of the persistent hypobaric hypoxia of life in the Andean altiplano.



Autor: Riquelme González, Raquel; - Herrera Videla, Emilio; - Ebensperger, Germán; - Krause, Bernardo; - Reyes, Roberto V.; - Sanhueza

Fuente: http://repositorio.uchile.cl/



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