Smooth-muscle contraction without smooth-muscle myosin

Nat Cell Biol. 2000 Jun;2(6):371-5. doi: 10.1038/35014065.

Abstract

Here we have used gene-targeting to eliminate expression of smooth-muscle myosin heavy chain. Elimination of this gene does not affect expression of non-muscle myosin heavy chain, and knockout individuals typically survive for three days. Prolonged activation, by KCl depolarisation, of intact bladder preparations from wild-type neonatal mice produces an initial transient state (phase 1) of high force generation and maximal shortening velocity, which is followed by a sustained state (phase 2) characterized by low force generation and maximal shortening velocity. Similar preparations from knockout neonatal mice do not undergo phase 1, but exhibit a normal phase 2. We propose that, in neonatal smooth muscle phase 1 is generated by recruitment of smooth-muscle myosin heavy chain, whereas phase 2 can be generated by activation of non-muscle myosin heavy chain. We conclude that phase 1 becomes indispensable for survival and normal growth soon after birth, particularly for functions such as homeostasis and circulation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Newborn
  • Blood Pressure / physiology
  • Body Weight
  • Cells, Cultured
  • Ductus Arteriosus, Patent / physiopathology
  • Female
  • Fluorescent Antibody Technique
  • In Vitro Techniques
  • Intestines / abnormalities
  • Intestines / physiology
  • Isoenzymes / deficiency
  • Isoenzymes / genetics
  • Isoenzymes / metabolism
  • Male
  • Mice
  • Mice, Knockout
  • Muscle Contraction / drug effects
  • Muscle Contraction / physiology*
  • Muscle, Smooth / abnormalities
  • Muscle, Smooth / cytology
  • Muscle, Smooth / drug effects
  • Muscle, Smooth / physiology*
  • Mutation / genetics
  • Myosin Heavy Chains / analysis
  • Myosin Heavy Chains / deficiency
  • Myosin Heavy Chains / genetics
  • Myosin Heavy Chains / physiology*
  • Potassium Chloride / pharmacology
  • Protein Isoforms / analysis
  • Protein Isoforms / deficiency
  • Protein Isoforms / genetics
  • Protein Isoforms / physiology
  • RNA, Messenger / analysis
  • RNA, Messenger / genetics
  • Renin / blood
  • Urinary Bladder / abnormalities
  • Urinary Bladder / cytology
  • Urinary Bladder / drug effects
  • Urinary Bladder / physiology

Substances

  • Isoenzymes
  • Protein Isoforms
  • RNA, Messenger
  • Potassium Chloride
  • Renin
  • Myosin Heavy Chains