INVESTIGADORES
COINTRY Gustavo Roberto
congresos y reuniones científicas
Título:
Tomographic and mechanical evaluation of muscle-bone interactions in mice artificially selected for body conformation
Autor/es:
GUSTAVO ROBERTO COINTRY; RICARDO DI MASSO; RICARDO FRANCISCO CAPOZZA; JOSÉ LUIS FERRETTI; MARÍA TERESA FONT
Lugar:
Calcidica (Grecia)
Reunión:
Congreso; IV International Workshop on Musculoskeletal and Neuronal Interactions; 2004
Institución organizadora:
International Society of Musculoskeletal and Neuronal Interactions
Resumen:
Antagonistic artificial selection of adult male and female mice with wide variation in body conformation produced animals with light body/long skeleton (CBi/L) or heavy body/short skeleton (CBi/C) from a parental line CBi. On changing the natural proportions between body and skeletal size/shape, this procedure provided an interesting model for analyzing correlations between the body and gastrocnemius weight and indicators of material, geometric and mechanical properties of cortical bone of femur diaphyses (as assessed by pQCT and bending tests) avoiding the natural, allometric associations which normally blunt the biomechanical interrelationships between muscles and bones. As expected, the selection procedure determined a wide inter-strain variation of the natural proportions between gastrocnemius mass, body weight (bw) and femur length, and between femur length and diaphyseal cross-sectional moment of inertia (CSMI). Analyzing all the animals as a whole, it was observed that  a. the CSMI correlated closer with gastrocnemius weight than it did with bw;  b. diaphyseal strength correlated significantly with CSMI, gastrocnemius weight and bw, and  c. correlation of CSMI with gastrocnemius weight was closer than with bw and was the only graph describing the studied association as a single (linear) function for all the 3 strains as a single group. Results suggest that 1. muscle mass would not depend alometrically on bw in any circumstance; 2. geometric proportions between long-bone length and cross-sectional properties would not be independent determinants of bone structure or strength; 3. muscle development would not depend on bone development; 4. the diaphyseal design would be adapted to muscle ability to directionally deform the skeleton rather than to the weight of the supported biomass, and 5. the biomechanical adaptation of bone strength to customary mechanical usage as allowed by the biochemical and microstructural constitution of the skeleton would be determined more closely by the dynamic influence of muscle contractions than by the static, gravitational load of the bw. Those relationships, difficult to assess in natural conditions, are crucial for interpreting the biomechanical homeostasis of the skeletal structure and the etiopathogenesis of all osteopenias and osteoporoses. This knowledge could be extrapolable to the pathogenetic analysis of many human bone-weakening diseases.