Hm. Greene et Sj. Wickler, Acute altitude exposure (3800 meters) and metabolic capacity in the middlegluteal muscle of equids, J EQUINE V, 20(3), 2000, pp. 194-197
Even relatively short exposure to high altitude can produce changes in the
metabolic capacity of muscle. This study examined the changes in citrate sy
nthase (CS), beta-hydroxyacyl-CoA-dehydrogenase (HOAD), lactate dehydrogena
se (LDH) and total protein (TP) activity of skeletal muscle in equids after
acute high altitude exposure (3800 m), The middle gluteal muscles of train
ed equids (one Quarter Horse. one Shetland pony, and four Arabians) were sa
mpled before altitude exposure (225 m) and after nine days of sub-maximal e
xercise at altitude (3800 m). Muscle biopsies were take from a location 10
cm dorsocaudal to the tuber coxae at an angle of 45 degrees. The insertion
site was standardized to a depth of 8 cm. Tissue homogenates were assayed f
or TP and maximal activity of CS, HOAD, and LDH, All samples were run in du
plicates and comparisons performed using a paired Student's t-test (signifi
cance set at P < 0.05), Altitude did not change CS, HOAD or TP. CS for pre-
altitude and altitude averaged 31.2 +/- 1.9 and 32.6 +/- 4.4 mu moles/g/min
, respectively (P = 0,51). HOAD values averaged 17.9 +/- 2.1 and 18.2 +/- 2
.9 mu moles/g/min, respectively (P = 0.85). Altitude acclimatization decrea
sed LDH activity. Pre-altitude and altitude LDH averaged 725.4 +/- 43.4 and
672.7 +/- 51.5 mu moles/g/min, respectively (P = 0.04). The decrease in LD
H is consistent with decreases in skeletal muscle observed in other mammals
at high altitude and suggests that muscles do not become more glycolyctic
in altitude hypoxia.