Identificador persistente para citar o vincular este elemento: http://hdl.handle.net/10553/6538
Título: Parasympathetic neural activity accounts for the lowering of exercise heart rate at high altitude
Autores/as: Boushel, R.
Calbet, JAL 
Radegran, Goran
Sondergaard, H.
Wagner, P.D.
Saltin, Bengt
Clasificación UNESCO: 241106 Fisiología del ejercicio
Palabras clave: Hypoxia
Altitude
Cardiac output
Heart rate
Exercise
Fecha de publicación: 2001
Publicación seriada: Circulation (New York, N.Y.) 
Resumen: BACKGROUND: In chronic hypoxia, both heart rate (HR) and cardiac output (Q) are reduced during exercise. The role of parasympathetic neural activity in lowering HR is unresolved, and its influence on Q and oxygen transport at high altitude has never been studied. METHODS AND RESULTS: HR, Q, oxygen uptake, mean arterial pressure, and leg blood flow were determined at rest and during cycle exercise with and without vagal blockade with glycopyrrolate in 7 healthy lowlanders after 9 weeks' residence at >/=5260 m (ALT). At ALT, glycopyrrolate increased resting HR by 80 bpm (73+/-4 to 153+/-4 bpm) compared with 53 bpm (61+/-3 to 114+/-6 bpm) at sea level (SL). During exercise at ALT, glycopyrrolate increased HR by approximately 40 bpm both at submaximal (127+/-4 to 170+/-3 bpm; 118 W) and maximal (141+/-6 to 180+/-2 bpm) exercise, whereas at SL, the increase was only by 16 bpm (137+/-6 to 153+/-4 bpm) at 118 W, with no effect at maximal exercise (181+/-2 bpm). Despite restoration of maximal HR to SL values, glycopyrrolate had no influence on Q, which was reduced at ALT. Breathing FIO(2)=0.55 at peak exercise restored Q and power output to SL values. CONCLUSIONS: Enhanced parasympathetic neural activity accounts for the lowering of HR during exercise at ALT without influencing Q. The abrupt restoration of peak exercise Q in chronic hypoxia to maximal SL values when arterial PO(2) and SO(2) are similarly increased suggests hypoxia-mediated attenuation of Q.
URI: http://hdl.handle.net/10553/6538
ISSN: 0009-7322
Fuente: Circulation[ISSN 0009-7322],v. 104 (15), p. 1785-1791
Colección:Artículos
miniatura
Parasympathetic neural activity accounts for the lowering of exercise heart rate at high altitude
Adobe PDF (93,99 kB)
Vista completa

Google ScholarTM

Verifica


Comparte



Exporta metadatos



Este elemento está sujeto a una licencia Licencia Creative Commons Creative Commons