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.

Assessment of Gastrointestinal Motility Using Three Different Assays In Vitro

“…Standard transducers are endowed with a calibrating screw, which can adjust the loading tension to the preparation, as required for different preparations and experimental conditions The tension applied to the muscle should be chosen to stretch the tissue to a length resulting in the greatest generated force on activation (Percy, 1996;Gad, 2000). To establish the optimum tension, pilot experiments are necessary, where the tissue response in function of applied tension is measured (Kenakin, 1998). Excessive tension values may cause a mechanical stress, resulting in a rise in spontaneous motility, related to the increase of prostaglandin synthesis and release in the tissue (Bennett, 1968(Bennett, , 1973.…”