title: Increased fiber capillarization in flight muscle of finch at altitude.
abstract: We examined fiber capillarization and ultrastructure in the highly aerobic flight muscle of six gray crowned rosy finches (Leucosticte arctoa; mass 22.9 +/- 0.5 (SE) g) living at altitude (A; White Mountains of Eastern California; 4000 m) compared to eight sea-level (SL) house finches (Carpodacus mexicanus, mass, 19.8 +/- 0.6 g) of the same subfamily, Carduelinae. Capillary length per fiber volume (A, 10,400 +/- 409 mm(-2); SL, 7513 +/- 423; P < 0.001) and capillary-to-fiber ratio (A, 2.32 +/- 0.07; SL, 1.85 +/- 0.06; P < 0.001) were significantly greater in A, with no difference in fiber cross-sectional area compared to SL. Capillary geometry was significantly different in A, yielding a greater contribution of tortuosity and branching to capillary length than in SL. Capillary-to-fiber surface ratio and fiber mitochondrial volume were both greater in A, but their ratio was similar to SL, indicating a proportional increase in the size of the capillary to fiber interface and fiber mitochondrial volume in A to sustain high levels of aerobic capacity while living at altitude.
authors.affiliation: Department of Medicine, University of California, San Diego, La Jolla 92093-0623, USA. odile@ucsd.edu
authors.forename: O
authors.initials: O
authors.lastname: Mathieu-Costello
authors.forename: P J
authors.initials: PJ
authors.lastname: Agey
authors.forename: L
authors.initials: L
authors.lastname: Wu
authors.forename: J M
authors.initials: JM
authors.lastname: Szewczak
authors.forename: R E
authors.initials: RE
authors.lastname: MacMillen
mesh_terms: D000222:Adaptation, Physiological; D000531:Altitude; D000818:Animals; D001717:Birds / Q000033:anatomy & histology* / Q000502:physiology; D002196:Capillaries / Q000033:anatomy & histology; D005260:Female; D005426:Flight, Animal / Q000502:physiology; D008297:Male; D008931:Mitochondria, Muscle / Q000648:ultrastructure; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000502:physiology / Q000648:ultrastructure; D010101:Oxygen Consumption