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Quantal sarcomere-length changes in relaxed single myofibrils

PainSci » bibliography » Blyakhman et al 2001
updated
Tags: biology, muscle

Two articles on PainSci cite Blyakhman 2001: 1. The Complete Guide to Trigger Points & Myofascial Pain2. Micro Muscles and the Dance of the Sarcomeres

original abstract Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.

We carried out experiments on single isolated myofibrils in which thin filaments had been functionally removed, leaving the connecting (titin) filaments as the sole agent taking up the length change. With technical advances that gave sub-nanometre detectability we examined the time course of single sarcomere-length change when the myofibril was ramp-released or ramp-stretched by a motor. The sarcomere-length change was stepwise. Step sizes followed a consistent pattern: the smallest was approximately 2.3 nm, and others were integer multiples of that value. The approximately 2.3-nm step quantum is the smallest consistent biomechanical event ever demonstrated. Although the length change must involve the connecting filament, the size of the quantum is an order of magnitude smaller than anticipated from folding of Ig- or fibronectin-like domains, implying either that folding occurs in sub-domain units or that other mechanisms are involved.

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