A comparison of muscle fiber characteristics at different levels of the vertebral column in the rhesus monkey

The vertebral muscle fiber characteristics of adult female rhesus monkeys have been examined. Muscle samples were obtained from precisely defined superficial and deep sites on both sides of the vertebral column. In particular, samples were collected from three different levels of the column and the muscle fiber characteristics from all these different sites were compared. It is clear that in the rhesus monkey at least, muscle fiber characteristics are dependent on the vertebral level although not necessarily on the side of the vertebral column.     

Torque-velocity characteristics and muscle fiber type in human vastus lateralis

The relationship between torque-velocity characteristics of the knee extensors during isokinetic contractions and muscle fiber type of the vastus lateralis, determined from two muscle biopsy samples, was investigated in 12 male and 18 female subjects. Peak torque, corrected for the effect of gravity and impact artifact, was classified as corrected peak torque. The torque measured 30 degrees from full extension and, corrected for gravity, was classified as corrected torque at 30 degrees. No significant correlations were found between the percentage of fast-twitch fibers (%FT) or the relative area of FT fibers (%FTA) and corrected peak torque values for any of the velocities tested or the knee angles where corrected peak torques were measured. However, significant inverse relationships were determined for corrected torque at 30 degrees at all but the fastest velocity (270 degrees/s) and both %FT and %FTA for the male subjects. These results reveal that muscle fiber type of the vastus lateralis, based on duplicate muscle samples, is not related to the peak torque actually generated by the knee extensors but may influence the shape of the torque output for maximal contractions sustained over the entire range of motion.     

Force-velocity characteristics of stomach muscle: a comparison between longitudinal and circular muscle strips

The longitudinal and circular muscle preparations from guinea pig stomach were compared in their property of shortening. The highest shortening speed was attained only for about 1 sec for longitudinal muscle and about 2 sec for circular muscle from the onset of stimulation in the course of tetanic contraction. Dynamic constants calculated from a force-velocity curve were almost independent of the muscle length, being set near its optimum length. Mean dynamic constants of the longitudinal muscle were: Vmax: 0.205 L/sec, b: 0.056 L/sec, a/Po: 0.292 and that of the circular muscle were: Vmax: 0.576 L/sec, b: 0.056 L/sec, a/Po: 0.107. The difference in Vmax of these muscles are discussed along with the difference in ultrastructure of the contractile filaments.     

Immunofluorescent subcellular localization of some muscle proteins: A comparison between tissue sections and isolated myofibrils

Summary The localization of parvalbumin in fish white muscle and of the calcium binding protein, of arginine kinase and of glycogen phosphorylase in crayfish tail muscle have been investigated by immunofluorescence using isolated myofibrils and muscle sections as starting materials.It is shown that the four proteins appear to be localized on the thin filaments when myofibrils are used as starting material. This result contrasts with previous observations where it appeared that parvalbumin in fish muscle and arginine kinase in crayfish muscle were distributed uniformly within the cell. This discrepancy is discussed in relation to the high solubility of these proteins.In the light of the present knowledge about striated muscles from these two organisms, it seems that the roles of parvalbumin in fish and of the calcium binding protein in crayfish are probably different.A preliminary report on this work was presented at the meeting of the Union of Swiss Societies for Experimental Biology, Zurich, 1977 (Benzonana et al., 1977a)     

Spaceflight effects on single skeletal muscle fiber function in the rhesus monkey

The purpose of this investigation was to understand how 14 days of weightlessness alters the cellular properties of individual slow- and fast-twitch muscle fibers in the rhesus monkey. The diameter of the soleus (Sol) type I, medial gastrocnemius (MG) type I, and MG type II fibers from the vivarium controls averaged 60 +/- 1, 46 +/- 2, and 59 +/- 2 microm, respectively. Both a control 1-G capsule sit (CS) and spaceflight (SF) significantly reduced the Sol type I fiber diameter (20 and 13%, respectively) and peak force, with the latter declining from 0.48 +/- 0.01 to 0.31 +/- 0.02 (CS group) and 0.32 +/- 0.01 mN (SF group). When the peak force was expressed as kiloNewtons per square meter (kN/m(2)), only the SF group showed a significant decline. This group also showed a significant 15% drop in peak fiber stiffness that suggests that fewer cross bridges were contracting in parallel. In the MG, SF but not CS depressed the type I fiber diameter and force. Additionally, SF significantly depressed absolute (mN) and relative (kN/m(2)) force in the fast-twitch MG fibers by 30% and 28%, respectively. The Ca(2+) sensitivity of the type I fiber (Sol and MG) was significantly reduced by growth but unaltered by SF. Flight had no significant effect on the mean maximal fiber shortening velocity in any fiber type or muscle. The post-SF Sol type I fibers showed a reduced peak power and, at peak power, an elevated velocity and decreased force. In conclusion, CS and SF caused atrophy and a reduced force and power in the Sol type I fiber. However, only SF elicited atrophy and reduced force (mN) in the MG type I fiber and a decline in relative force (kN/m(2)) in the Sol type I and MG type II fibers.     

Molecular evolution in the hypervariable regions of fetuin: comparison between human and African green monkey fetuin

Sequences of fetuin cDNA and its deduced amino acid residues from the African green monkey cell line Vero were found to differ by 7.3% and 12.9%, respectively, from the corresponding human sequences. Most amino acid substitutions were clustered within a small segment of the third domain (D3). Calculations of nonsynonymous and synonymous nucleotide substitution rates suggest that this small segment was mutated under positive selection. cDNAs encoding alpha1-antitrypsin, beta-actin and the sequences of intron 4 of alpha1-antitrypsin gene in human liver and Vero cells were also investigated. The results substantiated the positive selection imposed on the D3 segment.     

A new method for non-invasive estimation of human muscle fiber type composition

Background

It has been established that excellence in sports with short and long exercise duration requires a high proportion of fast-twitch (FT) or type-II fibers and slow-twitch (ST) or type-I fibers, respectively. Until today, the muscle biopsy method is still accepted as gold standard to measure muscle fiber type composition. Because of its invasive nature and high sampling variance, it would be useful to develop a non-invasive alternative.

Methodology

Eighty-three control subjects, 15 talented young track-and-field athletes, 51 elite athletes and 14 ex-athletes volunteered to participate in the current study. The carnosine content of all 163 subjects was measured in the gastrocnemius muscle by proton magnetic resonance spectroscopy (¹H-MRS). Muscle biopsies for fiber typing were taken from 12 untrained males.

Principal Findings

A significant positive correlation was found between muscle carnosine, measured by ¹H-MRS, and percentage area occupied by type II fibers. Explosive athletes had ∼30% higher carnosine levels compared to a reference population, whereas it was ∼20% lower than normal in typical endurance athletes. Similar results were found in young talents and ex-athletes. When active elite runners were ranked according to their best running distance, a negative sigmoidal curve was found between logarithm of running distance and muscle carnosine.

Conclusions

Muscle carnosine content shows a good reflection of the disciplines of elite track-and-field athletes and is able to distinguish between individual track running distances. The differences between endurance and sprint muscle types is also observed in young talents and former athletes, suggesting this characteristic is genetically determined and can be applied in early talent identification. This quick method provides a valid alternative for the muscle biopsy method. In addition, this technique may also contribute to the diagnosis and monitoring of many conditions and diseases that are characterized by an altered muscle fiber type composition.     

Immunofluorescent subcellular localization of some muscle proteins: a comparison between tissue sections and isolated myofibrils.

The localization of parvalbumin in fish white muscle and of the calcium binding protein, of arginine kinase and of glycogen phosphorylase in crayfish tail muscle have been investigated by immunofluorescence using isolated myofibrils and muscle sections as starting materials. It is shown that the four proteins appear to be localized on the thin filaments when myofibrils are used as starting material. This result contrasts with previous observations where it appeared that parvalbumin in fish muscle and arginine kinase in crayfish muscle were distributed uniformly within the cell. This discrepancy is discussed in relation to the high solubility of these proteins. In the light of the present knowledge about striated muscles from these two organisms, it seems that the roles of parvalbumin in fish and of the calcium binding protein in crayfish are probably different.     

Histogenesis of human esophageal striated muscle tissue

Development of the esophageal striated muscle tissue has been studied in 60 human embryos and fetuses at the age of 6-40 weeks. Stages in differentiation of the muscle fiber have been demonstrated, process of myofibrillogenesis has been studied. In the process of differentiation of the esophageal striated muscle fiber under the basal membrane myosatellitocytes are laid. A conclusion is made about myotomic origin of the human esophageal striated muscle tissue. The developmental peculiarity of the human esophageal striated muscle is formation between muscle fibers of specialized connections. This is explained by conditions of the esophageal functioning, that realizes peristaltic movements.