RESUMEN
In order to determine an aerobic diving limit (ADL) in emperor penguins (Aptenodytes forsteri), post-dive blood lactate concentrations were measured in penguins foraging at an isolated sea ice hole. Resting lactate concentrations were 1.2-2.7 mmol l-1. Serial samples revealed that lactate level usually peaked within 5 min after dives and that 7-12 min was required for lactate concentrations to decrease from 5-8 mmol l-1 to less than 2.5 mmol l-1. Post-dive lactate level was not elevated above 3 mmol l-1 for dives shorter than 5 min. Two-phase regression analysis revealed a transaction at 5.6 min in the post-dive lactate level versus diving duration relationship. All dives longer than 7 min were associated with lactate concentrations greater than 5 mmol l-1. We conclude that the ADL in emperor penguins ranges between 5 and 7 min. These are the first determinations of post-dive lactate concentrations in any free-diving bird and are currently the only physiological assessment of an ADL in an avian species.
Asunto(s)
Aves/fisiología , Buceo/fisiología , Ácido Láctico/sangre , Animales , Conducta AnimalRESUMEN
The case of a girl who was first seen at 3.5 years of age with longstanding asymptomatic heart block is reported. Electrophysiological study disclosed a block proximal to the His bundle. She grew up normally until the age of 11.5 years, when a syncopal attack occurred. Before a pacemaker could be inserted, she suffered a second fatal attack. Necropsy revealed a tumor of the atrioventricular node diagnosed as mesothelioma. Our findings are compared to the 38 cases already described in the literature.