Overview of Length‐Tension Relationships in Isolated Tissue

Abstract This unit describes critical aspects of preparing isolated tissues for experiments to determine the response of specific receptors in the tissue to compounds in a surrounding fluid bath. The two most common methods of evaluating muscle function in pharmacological length‐tension relationships experiments is through measuring isometric and isotonic contraction. In an isometric contraction, which occurs in muscles when they exert force without changing length, the contractile element shortens and the stress transmitted onto the series elastic component is measured in newtons or grams, reflecting the increase in total tension. Isotonic contraction is the shortening of a muscle under a constant load. A key factor in the sensitivity of an isolated tissue receptor system is the resting length under which the muscle is mounted. A discussion of important issues relating to resting length is included.