Fast fibres in a large animal: fibre types, contractile properties and myosin expression in pig skeletal muscles

Abstract

2B) with large differences inWe conclude that pig muscles express high proportions of fast MHC isoforms, including MHC-2B, and that Vo values are higher than expected on the basis of the scaling relationship between contractile parameters and body size.

New Insights into Muscle Fibre Types in Casertana Pig

“…Hill (1950) predicted that shortening velocity should scale as an allometric function of the body mass, with small animals possessing faster, more powerful muscles. Toniolo et al (2004) showed the scaling relation between V o and body mass and they showed that pig slow fibres conform to the values expected from the scaling equation obtained with other animal species (Pellegrino et al 2003). The resulting values concerning fast fibres were higher in the pig than those obtained in human fibres and similar to those of rabbit fibres (Pellegrino et al 2003).…”

Sensorimotor responsiveness and resolution in the giraffe

“…Furthermore, the measured force generation delay is approximately 46% larger than the 31.5ms delay observed in the rat, suggesting that force generation delay also increases with animal size. This is consistent with measured decreases in muscle fiber shortening velocity with increasing animal size (Rome et al, 1990;Toniolo et al, 2004). These size comparisons should be taken as tentative until these measurements are made using consistent methodology in animals spanning a wide size range.…”

“…Although the scaling relationship between muscle fiber length and body size has not been well characterized, muscle fibers in large animals, such as giraffes, are certainly longer than the corresponding whole-muscle length in small animals, such as rats (Alexander et al, 1981;Gans et al, 1989;Loeb and Richmond, 1994). Force generation delay reflects the time between force onset and the production of peak force; it is known that the maximum velocity of muscle fiber shortening decreases with animal size (Rome et al, 1990;Toniolo et al, 2004), suggesting that it will take larger animals more time to generate peak force.…”

Regulation of an antisense RNA with the transition of neonatal to IIb myosin heavy chain during postnatal development and hypothyroidism in rat skeletal muscle

“…The question arises then as to whether there is a mechanistic linkage between the absence of the conserved bII NAT promoter (and therefore absence of the bII NAT inhibitory transcript) and the presence of the IIb MHC in large mammals such as the kangaroo and opossum. In contrast to all other previously examined large body-size eutherians, the domesticated pig and llama, both of the Artiodactyla order, expresses the IIb MHC in apparently abundant proportions in certain skeletal muscles (16,56). Future research will be required to determine whether the bII NAT plays a role in inhibiting expression of IIb MHC in certain mammals, such as humans, and if a lack of bII NAT expression plays a mechanistic role in permitting IIb MHC transcription in other mammalian species.…”