TY - JOUR
T1 - Pauses, steps, and the mechanism of contraction.
AU - Pollack, G. H.
AU - Granzier, H. L.
AU - Mattiazzi, A.
AU - Trombitás, C.
AU - Periasamy, A.
AU - Baatsen, P. H.
AU - Burns, D. H.
PY - 1988
Y1 - 1988
N2 - Despite widespread controversy still surrounding the phenomenon, stepwise shortening has now been confirmed by five independent methods in this laboratory, and by several other methods in different laboratories. In this paper we offer preliminary evidence obtained with the most recent method--measurement of 'isotonic muscle length transients'. We find that the muscle length inflections observed after quick release to an isotonic load correspond to pauses and steps at the sarcomere level. Thus, pauses and steps are reflected not only in sarcomere length and segment length signals, but in the muscle length signal as well. We review several of the more illuminating features of stepwise shortening, as well as new ultrastructural observations which, taken together, point to an hypothesis for the generation of steps. The steps may be generated by shortening of one or another of the sarcomere's filaments: connecting filaments in the unactivated myofibril and thick filaments in the activated myofibril. Supporting evidence is considered.
AB - Despite widespread controversy still surrounding the phenomenon, stepwise shortening has now been confirmed by five independent methods in this laboratory, and by several other methods in different laboratories. In this paper we offer preliminary evidence obtained with the most recent method--measurement of 'isotonic muscle length transients'. We find that the muscle length inflections observed after quick release to an isotonic load correspond to pauses and steps at the sarcomere level. Thus, pauses and steps are reflected not only in sarcomere length and segment length signals, but in the muscle length signal as well. We review several of the more illuminating features of stepwise shortening, as well as new ultrastructural observations which, taken together, point to an hypothesis for the generation of steps. The steps may be generated by shortening of one or another of the sarcomere's filaments: connecting filaments in the unactivated myofibril and thick filaments in the activated myofibril. Supporting evidence is considered.
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M3 - Article
C2 - 3407536
AN - SCOPUS:0023746405
SN - 0065-2598
VL - 226
SP - 617
EP - 642
JO - Advances in experimental medicine and biology
JF - Advances in experimental medicine and biology
ER -