Muscle ultrastructure and biochemistry of lowland tibetans.
Kayser, Bengt, Hans Hoppeler, Dominique Desplanches, Claudio Marconi,
Barbara Broers, and Paolo Cerretelli.
D[acute]epartement de Physiologie, Centre M[acute]edical
Universitaire, 1211 Geneva 4, Switzerland; Anatomisches Institut,
Universit[umlaut]at Bern, B[umlaut]uhlstrasse, 1000 Berne,
Switzerland, Switzerland; Consiglio Nazionale delle Ricerche - ITBA
Fisiologia, Via Amp[grave]ere 56, Milano, Italy; URA 1341 CNRS,
Laboratoire de Physiologie, Universit[acute]e Claude Bernard, 69373
Lyon, France
APStracts 3:0089A, 1996.
Muscle ultrastructure and biochemistry in vastus lateralis muscle
biopsies and the response to exercise of 8 lowland Tibetans (T) were
compared to those of 8 Nepalese lowlanders (N). Blood hemoglobin was
lower in T than in N (119+/-3 vs 131+/-2 g.l-1, P<0.05). peak/kg
bm was similar (37.9+/-2.2 _T_ vs. 40.1+/-1.36 ml.kg-1 bw _N_).
Maximum exercise blood lactate was the same (11.4+/-0.5 vs 11.3+/-0.6
mM). Muscle fiber type distribution was similar (type I 58.6+/-3.4
_N_ vs 57+/-3.4% _T_, type IIa 24.1+/-3.5 vs 22.3+/-2.9%, type IIb
17.4+/-1.4 vs 15.9+/-2.9%). The Tibetans had smaller fiber cross
sectional areas (3413+/-677 _T_ vs 3895+/-447 [mu][mu]2 _N_,
P<0.05) but had similar number of capillaries per muscle fiber
(1.35+/-0.23 _T_ vs 1.46+/-0.08 [N]) and per muscle fiber area
(399+/-29 _T_ vs 382+/-65 mm-2 _N_). Total mitochondrial volume
density was much lower in _T_ (3.99+/-0.17 than in _N_ 5.51+/-0.19%)
(P<0.025). Paralleling mitochondrial volume density, citrate
synthase and 3-hydroxy-acyl-CoA dehydrogenase activity were lower in
T than in N (P<0.05). The activities of lactate dehydrogenase
and hexokinase were the same in both groups. T had significantly less
muscle fiber lipid droplets then N which correlated with the low
activity of 3-hydroxy-acyl-CoA dehydrogenase (r=0.57, p=0.02). In
conclusion, lowland born Tibetans have a low mitochondrial
volume/specific peak ratio, which, based on previous measurements on
altitude Sherpas (Kayser et al., J. Appl. Physiol. 70; 1938-1942,
1991) appears to be an inborn feature.
Received 11 October 1995; accepted in final form 31 January 1996.
APS Manuscript Number A1098-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 14 February 96