Reinhard Bauer, Tomasz Gedrange, Kathrin Bauer, Bernd Walter
Intrauterine growth restriction induces increased capillary density and accelerated type I fiber maturation in newborn pig skeletal muscles
Aims: Humans with low birth weight exhibit evidences of vascular dysfunction. Recent findings indicate a microvascular rarefaction in skeletal muscles soon after postnatal development in rats suffered by intrauterine protein restriction.
Methods: To examine the effects of intrauterine growth restriction on capillary density, muscle fiber distribution and accompanying muscular and systemic circulation immediately after birth, studies were conducted on 1-day-old anesthetized normal weight (n=7) and intrauterine growth restricted (n=6) piglets. Cardiac output and hind limb muscle blood flow were measured by colored microspheres. Counting of type I fibers and skeletal capillary numbers was done by immunohistochemical staining.
Results: Increased proportion of type I fibers and capillary density was found in the flexor digitalis superficialis and gastrocnemius medialis (P<0.05) in newborn IUGR piglets. Furthermore, a marked correlation was shown between capillary density and type I fiber fraction for all flexor muscles studied (P<0.05). Moreover, cardiac output and muscular blood flow were markedly increased in IUGR piglets (P<0.05). Correspondingly, total peripheral resistance, as well as vascular resistance, of hind limb flexors appeared significantly decreased (P<0.05).
Conclusions: Compromised intrauterine environmental conditions leading to fetal growth restriction provokes coordinated structural and functional adaptation of skeletal muscles.
Journal of Perinatal Medicine, Walter de Gruyter
Print ISSN: 1619-3997
Volume: 34, 05/2006
Pages: 235 - 242
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