Contractile properties of skeletal muscle fibres and heart tissue
The permeabilised single muscle fibre system shown below consists of various components to accurately measure the contractile properties of a muscle fibre.
Properties of muscle that can be measured include:
☆ shortening velocity
☆ calcium sensitivity of fibres
☆ effects of drugs on contractility parameters
The upper limit of the force transducer is 5.1 mNewton, with a maximum recording frequency of 1000 Hz.
Muscle fibres can be submerged into 8 different temperature controlled baths, which can be set between 10˚C and 50˚C. Each bath can contain solutions that block contraction (e.g. inhibitors), activate the fibre (e.g. ATP, calcium) or enhance contraction (e.g. drugs).
The lever arm connected to the motor is able to control the length of the muscle fibre by stretching it or allowing the fibre to shorten during contraction. This lever can be programmed to produce rapid stretching or shortening (within 1 ms) or gradually over extended periods. The apparatus is mounted on an inverted microscope equipped with a pre-calibrated CMOS camera, allowing for the accurate measurement of the specimen length, diameter and sarcomere spacing.
Can the system be used for other tissues or materials?
Yes. Creativity would be at the order of the day. This system is specifically designed to withstand forces less than 5.1 mNewton. Therefore, other tissues (e.g. small pieces of heart valve) or synthetics that cannot produce force (e.g. hydragels, thin synthetic filaments) could be attached to the force transducer and lever arm. By using the lever arm to actively stretch the connected substance, parameters such as elasticity, length-tension curves or breaking force could be measured.