Decreased skeletal muscle capillary density is related to higher serum levels of low-density lipoprotein cholesterol and apolipoprotein B in men

The relationships between skeletal muscle morphology, particularly muscle f iber capillary density, and serum lipid profiles were evaluated in 25 non-o bese men aged 18 to 36 years (body mass index [BMI], 22.7 +/- 2.5 kg/m(2); body fat, 13.6% +/- 4.0%, maximal oxygen uptake [(V) over dot o(2)max], 46. 2 +/- 6.3 ml/kg/min). Skeletal muscle samples were taken from the vastus la teralis using the needle-biopsy method. The fiber types (I, IIa, and IIx) a nd their percent distribution, the indices of capillary density, and the di ffusion index expressed as the cross-sectional area occupied by one capilla ry were determined. Blood samples were drawn from the antecubital vein afte r a 12-hour fast. Based an Pearson's correlation analysis, the number of ca pillaries around type IIx fiber correlated inversely with the serum level o f tow-density lipoprotein cholesterol ([LDL-C] r = -.50, P < .05). The numb er of capillaries per fiber (cap/fiber ratio), number of capillaries per ar ea (cap/mm(2)), and capillaries around each fiber type correlated inversely with the serum level of apolipoprotein B ([apo B] r = -.40 to -.54, P < .0 5 to.01). Further, the diffusion index for each fiber type correlated posit ively with LDL-C and apo B (r = .42 to .50, P < .05 to.01). Among 14 subjec ts in whom high-density lipoprotein cholesterol (HDL-C) subfractions were a nalyzed, a positive correlation was found between cap/mm(2) and HDL2-C (r = .64, P < .05). Partial correlation analysis showed that these correlations either remain or improve after adjusting for age, (V) over dot o(2)max, an d body fatness. These results indicate that skeletal muscle capillary densi ty and diffusion capacity are related to lipid and apolipoprotein concentra tions for both type I and type II fibers. Copyright (C) 1999 by W.B. Saunde rs Company.