title: Passive stiffness of rat skeletal muscle undernourished during fetal development.
abstract: OBJECTIVE
  The aim of the study was to investigate the effect of fetal undernutrition on the passive mechanical properties of skeletal muscle of weaned and young adult rats.
  
  
  BACKGROUND
  A poor nutrition supply during fetal development affects physiological functions of the fetus. From a mechanical point of view, skeletal muscle can be also characterized by its resistance to passive stretch.
  
  
  METHODS
  Male Wistar rats were divided into two groups according to their mother's diet during pregnancy: a control group (mothers fed a 17% protein diet) and an isocaloric low-protein group (mothers fed a 7.8% protein diet). At birth, all mothers received a standardized meal ad libitum. At the age of 25 and 90 days, the soleus muscle and extensor digitorum longus (EDL) muscles were removed in order to test the passive mechanical properties. A first mechanical test consisted of an incremental stepwise extension test using fast velocity stretching (500 mm/s) enabling us to measure, for each extension stepwise, the dynamic stress (σd) and the steady stress (σs). A second test consisted of a slow velocity stretch in order to calculate normalized stiffness and tangent modulus from the stress-strain relationship.
  
  
  RESULTS
  The results for the mechanical properties showed an important increase in passive stiffness in both the soleus and EDL muscles in weaned rat. In contrast, no modification was observed in young adult rats.
  
  
  CONCLUSIONS
  The increase in passive stiffness in skeletal muscle of weaned rat submitted to intrauterine undernutrition it is most likely due to changes in muscle passive stiffness.
authors.affiliation: Centro Acadêmico de Vitória, Universidade Federal de Pernambuco, Vitória de Santo Antão, Pernambuco, Brazil.
authors.forename: Ana Elisa
authors.initials: AE
authors.lastname: Toscano
authors.forename: Karla Monica
authors.initials: KM
authors.lastname: Ferraz
authors.forename: Raul Manhães de
authors.initials: RM
authors.lastname: Castro
authors.forename: Francis
authors.initials: F
authors.lastname: Canon
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D018753:Diet, Protein-Restricted / Q000009:adverse effects; D004548:Elasticity / Q000502:physiology*; D005260:Female; D047109:Fetal Development / Q000502:physiology*; D008297:Male; D044342:Malnutrition / Q000150:complications*; D023421:Models, Animal; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000503:physiopathology*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000503:physiopathology*; D039401:Prenatal Nutritional Physiological Phenomena / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D012026:Reflex, Stretch / Q000502:physiology*; D014886:Weaning