l>Length tension of MuscleLab LT: Frog Sartorius Muscle Length-Tension Curve


The passive elastic properties of muscles have the right to be modelled as nonlinear springs. Your force-tension curve becomes exponentially steeper at longer lengths of stretch.

In addition to the passive force when the muscle is engendered it contracts to develop an energetic force. This active force is obtained from interaction of the actin and myosin filaments. The energetic force length tension curve is defined by sliding Filament model and has its maximum at the muscle"s regular resting size in the body. In ~ this length there is the many interaction between the actin and also myosin filaments audit for the largest active force production. At longer lengths the filaments have actually less chance for forming cross-bridges and also therefore produce less force. A the muscle deceases in size past the resting size the filaments become much more closely packed and are may be to form fewer cross-bridges.


relates come Hooke"s Law, yet nonlinear. assume muscle can be modelled together a nonlinear spring. Gastrocnemius or sartorius muscle


(1) Dissection because that sartorius muscle and sciatic nerve. We"ll use Rana Pipiens, the leopard frog. Pithing, exposure the sciatic nerve TA or JD will carry out dissection (unless a premed would favor to try...)

Pithing is used to euthanize the frogs through scrambling the CNS. A sharp, pointed probe is put through the skin right into the foramen magnum in between the basic of the skull and also the height of the vertebrae. (midline in ~ the level of the caudal typanic oval).

Once the CNS has actually been scrambled, the spinal cord should be destroyed to suppress any reflexes that can disturb the experiment. The method should it is in attempted only after obtaining knowledge the anatomy making use of skeletons, and also after a period of training including practice on dead animals. This method could activate pain receptors if the ideal regions that the cord space not completely destroyed.

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Incisions, surgical procedure to reveal sciatic nerve, and relate to stimulator. frog, dissection tray, gloves, instruments to use: foreceps, tweezers, pins, glass probe, scissors, Ringer"s solution, 2-0 silk thread.

link come Dissection

use the Ringer"s equipment for exposed tissue. Description: also known together Ringer’s irrigation: A systems of recently boiled distilled water comprise 8.6 gm salt chloride, 0.3 gm potassium chloride, and 0,33 gram calcium chloride per litre – the very same concentrations as their event in body fluids. Ingredient are: NaCL 6 g, KCL 0,075 g, CaCl2 0,1 g, NaHCO3 0,1 g.

specifically for amphibians: 6.5 g NaCl 0.42 g KCl 0.25 g CaCl2 1 liter dH2O

Ringer experimented with assorted solutions containing the chlorides that sodium, potassium, calcium and also magnesium, in stimulate to obtain a perfect physiological saline equipment which would save the love beating outside of the body. Several various formulas are now used. Variants are called Locke"s or Tyrode"s solution. Locke"s, or Ringer-Locke solution, containins an ext glucose and sodium, and is an especially used because that mammals.


Securely pin down the frog just above the knee, no part of the preperation should move consisting of the dissection pan. Affix the subject tied come the Achilles tendon to the force transducer utilizing an S hook. Readjust the length between the force transducer and the frog muscle prepartation in the tray so that it is just zero together the object is simply less than taut (your very first active stress reading have to be 0). Connect the stimulating electrodes come a Narishige micromanipulator stand and adjust them so the the sciatic nerve is elevated the end of body and resting ~ above the end of the electrode.

Make every the connections between the muscle preparation and also the stimulator, oscilloscope and also computer. The stimulating electrodes should be linked the stimulator. Set the stimulator to a frequency the 0.2 Hz, start with manual stimulation by setup the output mode switch come the single position and also use the current option, (not the voltage). To find the excitation threshold set the current to 0 and also trigger the stimulator and look for a twitch, if you have actually it hooked increase you should have the ability to see that on the oscilloscope, progressively increase the existing until you have reached the preferably twitch tension, then rise the present by around 10% come ensure a supra-maximal stimulus. You can start with the oscilloscope at a time basic of 1 msec/div and vertically 0.1-0.01 Volts/div. Trigger set on the exterior input and the triggering level control to change to trigger the oscilloscope sweep as soon as the stimulator is activated. Friend may also want an electrode to document the activity potentials in the nerve and/or muscle (to see contraction freq/tetanus) these need to be attached to the oscilloscope and computer with a pre-amp. The pre-amp should have the entry in differential setting with a obtain of one of two people 100 or 1000; if possible include band happen filters (10 Hz low pass and 3 kHz high pass). The force transducer should likewise be hooked as much as the computer system so the you deserve to record the pressures at the miscellaneous lengths. exposure the sciatic nerve, trial and error

(2) Measure length tension of frog gastrocnemius (calf) or sartorius (thigh)muscle use of pressure transducer: specs, springs.

Create LabVIEW vi to capture triggered waveforms and inspect because that maximum and steady stable state (passive) data. to check out data and generate curves.

measuring length: Narishige micromanipulator to stretch muscle. attachment to muscle by silk thread. Mechanically deviation of force transducer?

Explore use of the stimulator (single pulse) to cause maximal twitch; document twitch ~ above "scope and also pick turn off maximum and steady state (passive) data points.

Show the passive and active L-T curve from a quick muscle length when stress is zero to a "maximum" length when tension is about 80-100 grams. Exactly how reproducible is the curve?

Frog Physiology Respiration, manage temperature, muscle fiber types. Fast, slow The short fibers gastrocnemius and also a higher amount of connective tissue execute not display a local maximum in the full length anxiety curve.

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In comparison, the longer, parallel muscle yarn of the sartorius add less come the passive tension and also therefore present a local maximum in the total length anxiety curve.