The effects of a calcium dependent protease on the ultrastructure and contractile mechanics of skinned uterine smooth muscle

Joe R. Haeberle, Sharon A. Coolican, Andrew Evan, David R. Hathaway

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

In situ substrates for a vascular smooth muscle calcium-dependent protease (CDP) were investigated using a chemically skinned uterine smooth muscle preparation. Treatment of skinned smooth muscles with CDP had no effect on the total content of actin and myosin. Electron microscopical observations demonstrated that membrane plaques, cytoplasmic dense bodies, and intermediate filaments were all degraded by CDP. In addition, CDP reduced both isometric force and isotonic shortening velocity of contracted muscles in a concentration and time-dependent manner. Treatment of contracting muscles with CDP resulted in a condensation of myofilaments away from the plasma membrane concurrent with the loss of contractility. The condensation of myofilaments was ATP-dependent and could be inhibited by removal of ATP prior to proteolysis. The effects of proteolysis on smooth muscle ultrastructure and contractility support previously proposed models which assign a role to cytoskeletal elements in coordinating the molecular interaction of actomyosin to produce muscle contraction. The loss of cytoskeletal structures following protease treatment suggests that one of the functions of CDP in smooth muscle may be the disassembly of the cell cytoskeleton.

Original languageEnglish (US)
Pages (from-to)347-363
Number of pages17
JournalJournal of Muscle Research and Cell Motility
Volume6
Issue number3
DOIs
StatePublished - Jun 1 1985

ASJC Scopus subject areas

  • Biochemistry
  • Physiology
  • Cell Biology

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