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Characteristics of tetanic force produced by the sternomastoid muscle of the rat.

Sobotka S, Mu L - J. Biomed. Biotechnol. (2010)

Bottom Line: It also has unique anatomical advantages that allow its wide use in head and neck tissue reconstruction and muscle reinnervation.However, little is known about its contractile properties.These data are important not only to better understand the contractile properties of the rat SM muscle, but also to provide normative values which are critical to reliably assess the extent of functional recovery following muscle reinnervation.

View Article: PubMed Central - PubMed

Affiliation: Department of Research, Upper Airway Research Laboratory, Hackensack University Medical Center, Hackensack, NJ 07601, USA.

ABSTRACT
The sternomastoid (SM) muscle plays an important role in supporting breathing. It also has unique anatomical advantages that allow its wide use in head and neck tissue reconstruction and muscle reinnervation. However, little is known about its contractile properties. The experiments were run on rats and designed to determine in vivo the relationship between muscle force (active muscle contraction to electrical stimulation) with passive tension (passive force changing muscle length) and two parameters (intensity and frequency) of electrical stimulation. The threshold current for initiating noticeable muscle contraction was 0.03 mA. Maximal muscle force (0.94 N) was produced by using moderate muscle length/tension (28 mm/0.08 N), 0.2 mA stimulation current, and 150 Hz stimulation frequency. These data are important not only to better understand the contractile properties of the rat SM muscle, but also to provide normative values which are critical to reliably assess the extent of functional recovery following muscle reinnervation.

No MeSH data available.


Related in: MedlinePlus

A representative example in an individual rat to show the relation between muscle force and stimulation frequency at two levels of stimulation current. The passive tension was at a moderate level (0.08 N). The nerve stimulation current was 0.1 mA (continuous line) or 0.075 mA (dashed line). Muscle force is higher for a bigger current but otherwise both curves share similar characteristics with a slight decline of force for the highest frequency of stimulation.
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fig7: A representative example in an individual rat to show the relation between muscle force and stimulation frequency at two levels of stimulation current. The passive tension was at a moderate level (0.08 N). The nerve stimulation current was 0.1 mA (continuous line) or 0.075 mA (dashed line). Muscle force is higher for a bigger current but otherwise both curves share similar characteristics with a slight decline of force for the highest frequency of stimulation.

Mentions: We also analyzed how muscle force changes with regard to the frequency of stimulation pulses (from 0 to 500 Hz). We used a 200 ms train of 0.1 mA pulses. The muscle was stretched with a moderate tension (0.08 N). Figure 5 illustrates in a representative rat the muscle force in response to 6 different frequencies of stimulation (maximal values of force for each frequency were measured to create a frequency-force curve). Stimulation pulses below 25 Hz produced individual twitches of the muscle in response to each pulse separately, with a small summation of responses observed already at 25 Hz. The frequency-density relationship of muscle force (normalized by cross-section area of the muscle) in the group data is shown in Figure 6. Muscle force increased with stimulation frequency, starting at 25 Hz (with almost a full tetanic fusion of force at 50 Hz) and reached maximal value at 150 Hz. Further increases of stimulation frequency (above 300 Hz) produced a small but consistent decrease of muscle force. The muscle force generated by the stimulation train of 500 Hz (the highest frequency used in this study) was 21% smaller than that generated by the stimulation of 150 Hz. The difference was statistically significant (P < .01, t = 3.5, two-tailed t-test for pairs, df = 11). A similar shape of the frequency-force relationship was seen for different stimulation currents (see Figure 7).


Characteristics of tetanic force produced by the sternomastoid muscle of the rat.

Sobotka S, Mu L - J. Biomed. Biotechnol. (2010)

A representative example in an individual rat to show the relation between muscle force and stimulation frequency at two levels of stimulation current. The passive tension was at a moderate level (0.08 N). The nerve stimulation current was 0.1 mA (continuous line) or 0.075 mA (dashed line). Muscle force is higher for a bigger current but otherwise both curves share similar characteristics with a slight decline of force for the highest frequency of stimulation.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2875700&req=5

fig7: A representative example in an individual rat to show the relation between muscle force and stimulation frequency at two levels of stimulation current. The passive tension was at a moderate level (0.08 N). The nerve stimulation current was 0.1 mA (continuous line) or 0.075 mA (dashed line). Muscle force is higher for a bigger current but otherwise both curves share similar characteristics with a slight decline of force for the highest frequency of stimulation.
Mentions: We also analyzed how muscle force changes with regard to the frequency of stimulation pulses (from 0 to 500 Hz). We used a 200 ms train of 0.1 mA pulses. The muscle was stretched with a moderate tension (0.08 N). Figure 5 illustrates in a representative rat the muscle force in response to 6 different frequencies of stimulation (maximal values of force for each frequency were measured to create a frequency-force curve). Stimulation pulses below 25 Hz produced individual twitches of the muscle in response to each pulse separately, with a small summation of responses observed already at 25 Hz. The frequency-density relationship of muscle force (normalized by cross-section area of the muscle) in the group data is shown in Figure 6. Muscle force increased with stimulation frequency, starting at 25 Hz (with almost a full tetanic fusion of force at 50 Hz) and reached maximal value at 150 Hz. Further increases of stimulation frequency (above 300 Hz) produced a small but consistent decrease of muscle force. The muscle force generated by the stimulation train of 500 Hz (the highest frequency used in this study) was 21% smaller than that generated by the stimulation of 150 Hz. The difference was statistically significant (P < .01, t = 3.5, two-tailed t-test for pairs, df = 11). A similar shape of the frequency-force relationship was seen for different stimulation currents (see Figure 7).

Bottom Line: It also has unique anatomical advantages that allow its wide use in head and neck tissue reconstruction and muscle reinnervation.However, little is known about its contractile properties.These data are important not only to better understand the contractile properties of the rat SM muscle, but also to provide normative values which are critical to reliably assess the extent of functional recovery following muscle reinnervation.

View Article: PubMed Central - PubMed

Affiliation: Department of Research, Upper Airway Research Laboratory, Hackensack University Medical Center, Hackensack, NJ 07601, USA.

ABSTRACT
The sternomastoid (SM) muscle plays an important role in supporting breathing. It also has unique anatomical advantages that allow its wide use in head and neck tissue reconstruction and muscle reinnervation. However, little is known about its contractile properties. The experiments were run on rats and designed to determine in vivo the relationship between muscle force (active muscle contraction to electrical stimulation) with passive tension (passive force changing muscle length) and two parameters (intensity and frequency) of electrical stimulation. The threshold current for initiating noticeable muscle contraction was 0.03 mA. Maximal muscle force (0.94 N) was produced by using moderate muscle length/tension (28 mm/0.08 N), 0.2 mA stimulation current, and 150 Hz stimulation frequency. These data are important not only to better understand the contractile properties of the rat SM muscle, but also to provide normative values which are critical to reliably assess the extent of functional recovery following muscle reinnervation.

No MeSH data available.


Related in: MedlinePlus