|
|
|
|
|
|
|
||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Address correspondence to Anders Arner, Department of Physiological Sciences, BMC F11, Tornavägen 10, SE-221 84 Lund, Sweden. Fax: (46) 46 222 7765; E-mail: Anders.Arner{at}mphy.lu.se
Nonmuscle myosin can generate force and shortening in smooth muscle, as revealed by studies of the urinary bladder from mice lacking smooth muscle myosin heavy chain (SM-MHC) but expressing the nonmuscle myosin heavy chains A and B (NM-MHC A and B; Morano, I., G.X. Chai, L.G. Baltas, V. Lamounier-Zepter, G. Lutsch, M. Kott, H. Haase, and M. Bader. 2000. Nat. Cell Biol. 2:371–375). Intracellular calcium was measured in urinary bladders from SM-MHC–deficient and SM-MHC–expressing mice in relaxed and contracted states. Similar intracellular [Ca2+] transients were observed in the two types of preparations, although the contraction of SM-MHC–deficient bladders was slow and lacked an initial peak in force. The difference in contraction kinetics thus do not reflect differences in calcium handling. Thick filaments were identified with electron microscopy in smooth muscle cells of SM-MHC–deficient bladders, showing that NM-MHC can form filaments in smooth muscle cells. Maximal shortening velocity of maximally activated, skinned smooth muscle preparations from SM-MHC–deficient mice was significantly lower and more sensitive to increased MgADP compared with velocity of SM-MHC–expressing preparations. Active force was significantly lower and less inhibited by increased inorganic phosphate. In conclusion, large differences in nucleotide and phosphate binding exist between smooth and nonmuscle myosins. High ADP binding and low phosphate dependence of nonmuscle myosin would influence both velocity of actin translocation and force generation to promote slow motility and economical force maintenance of the cell.
Key Words: nonmuscle myosin • urinary bladder • ATP • ADP • phosphate
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
|
|
 |
|
  R. S. Scott, Z. Li, D. Paulin, B. Uvelius, J. V. Small, and A. Arner Role of desmin in active force transmission and maintenance of structure during growth of urinary bladder Am J Physiol Cell Physiol, August 1, 2008; 295(2): C324 - C331. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. J. Eddinger and D. P. Meer Myosin II isoforms in smooth muscle: heterogeneity and function Am J Physiol Cell Physiol, August 1, 2007; 293(2): C493 - C508. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. E. Speich, K. Quintero, C. Dosier, L. Borgsmiller, H. P. Koo, and P. H. Ratz A mechanical model for adjustable passive stiffness in rabbit detrusor J Appl Physiol, October 1, 2006; 101(4): 1189 - 1198. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Ekman, K. Fagher, M. Wede, K. Stakeberg, and A. Arner Decreased Phosphatase Activity, Increased Ca2+ Sensitivity, and Myosin Light Chain Phosphorylation in Urinary Bladder Smooth Muscle of Newborn Mice J. Gen. Physiol., January 31, 2005; 125(2): 187 - 196. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Dobaczewski, S. Akrivakis, K. Nasser, L. H. Michael, M. L. Entman, and N. G. Frangogiannis Vascular Mural Cells in Healing Canine Myocardial Infarcts J. Histochem. Cytochem., August 1, 2004; 52(8): 1019 - 1029. [Abstract] [Full Text] [PDF]
|
|
|
|
