The Gastrocnemius Muscle of Rana pipiens is an Appropriate Model for Skeletal Muscle Contractile Kinetics When Compared to Peer-Reviewed Models

Georgia Institute of Technology

BMED 3110: Quantitative Engineering Physiology Laboratory I

Section B: Team Baboons

16 November 2014

ABSTRACT

The dynamics of skeletal muscle kinetics can be quantified using various experimental methods involving stimulated muscle contractions. Performing these experiments under isometric and isotonic conditions can help diagnose diseases relating to muscle dysfunctions. It was hypothesized that the model for skeletal muscle contractile kinetics created by testing the gastrocnemius muscle of a Rana pipiens would resemble peer-reviewed models. Muscle
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Velocity was calculated by finding the change in position of the indicators between each frame and multiplying by the frame rate (30 fps) and maximum instantaneous velocity was paired with the weight applied to fit to the Hill equation. Guesses for F0, a, and b were taken from the isometric experiment and literature values.6

RESULTS

Figure 3: Length-Tension behavior of the gastrocnemius of a Rana pipiens compared to expected data from peer-reviewed literature. The gastrocnemius of a Rana pipiens (n=1) was stimulated in situ isometrically. Experimentally measured tensions (red squares) were plotted with literature values (green circles). Tensions at corresponding normalized lengths were compared between literature and measured values and were comparing using piecewise linear regression in groups of three yielding an overall r2isometric = 0.956033 between measured values and expected results from
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The measured tensions were normalized relative to the maximum tension and the lengths were normalized relative to the length at which maximum force was generated (Ln = 29 mm). The measured data and expected data were plotted together (Figure 3). Correlation between measured and expected tensions at the same normalized lengths was determined for the three expected segments of the length-tension relationship.2,3,4 This was done using piecewise linear regression and yielded r2isometric = 0.956033. The fitted curve for the isotonic experiment resulted in r2isotonic = 0.960557. The F0 was 19.5 N for the fit and 6.35 N for the guess. In addition, the 95% confidence interval for b is greater than the value of b