PMID: 3752236Sep 1, 1986Paper

Time dependence of shortening velocity in tracheal smooth muscle

The American Journal of Physiology
N L StephensC S Packer

Abstract

It seems fairly well established that in the early phase of smooth muscle contraction cross bridges cycle at a relatively rapid rate. Later on these are replaced by very slowly cycling cross bridges or "latch bridges," operating with high economy. We describe a method to identify the time at which the transition occurs. By abruptly applying a light afterload at varying time intervals after stimulation of a canine tracheal smooth muscle, a point in time could be identified when cross-bridge cycling slowed. This was called the transition time. Because this transition was load dependent, the study was repeated with the preload abruptly reduced to zero. This permitted analysis of data in terms of cross-bridge activity. Maximum zero load velocity (Vo) of the contractile machinery was plotted against time and yielded a biphasic curve. The descending limb of the curve was fitted by a curve of the form Vo(t) = alpha e-K1t + beta e-K2t; K1 was almost three times greater than K2. We speculate that the faster rate constant represented activity of the early rapidly cycling cross bridges, and the slower constant reflected cycling rates in the latch state. These results are consistent with the latch bridge hypothesis put forward by Dillon et...Continue Reading

References

Jul 1, 1978·Proceedings of the Society for Experimental Biology and Medicine·J DiSalvoP Silver
Jun 1, 1974·The American Journal of Physiology·N L Stephens, C M Skoog
Oct 22, 1971·Nature·A F Huxley, R M Simmons
Jun 1, 1971·The American Journal of Physiology·N L Stephens, U Kromer
Jul 1, 1971·Circulation Research·D L BrutsaertE H Sonnenblick
Jun 1, 1969·Journal of Applied Physiology·N L StephensJ A Mehta
May 1, 1966·The Journal of Physiology·A M GordonF J Julian
Apr 1, 1984·Physiological Reviews·G Gabella
Nov 1, 1983·Journal of Applied Physiology: Respiratory, Environmental and Exercise Physiology·R W Mitchell, N L Stephens
Nov 1, 1980·The Journal of General Physiology·M J SiegmanR E Davies

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Citations

May 13, 2009·Pediatric Pulmonology·Rachel E LaudadioSteven P Driska
Oct 1, 1988·Pflügers Archiv : European journal of physiology·C S PackerN L Stephens
Oct 1, 2003·Respiratory Physiology & Neurobiology·Newman L StephensXuefei Ma

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