Single Rabbit Stomach Smooth Muscle Cell Myosin Heavy Chain SMB Expression and Shortening Velocity

Authors

Thomas J. Eddinger, Marquette UniversityFollow
Daniel P. Meer, Cardinal Stritch University

Document Type

Article

Language

eng

Format of Original

8 p.

Publication Date

2-2001

Publisher

American Physiological Society

Source Publication

American Journal of Physiology - Cell Physiology

Source ISSN

0002-9513

Original Item ID

DOI: 10.1152/ajpcell.2001.280.2.C309

Abstract

Isolated single smooth muscle cells (SMCs) from different regions of the rabbit stomach were used to determine a possible correlation between unloaded shortening velocity and smooth muscle (SM) myosin heavy chain (MHC) S1 head isoform composition (SMA, no head insert; SMB, with head insert). α-Toxin-permeabilized isolated single cells were maximally activated to measure unloaded shortening velocity and subsequently used in an RT-PCR reaction to determine the SMA/SMB content of the same cell. SM MHC SMA and SMB isoforms are uniquely distributed in the stomach with cells from the fundic region expressing little SMB (38.1 ± 7.3% SMB; n = 16); cells from the antrum express primarily SMB (94.9 ± 1.0% SMB; n = 16). Mean fundic cell unloaded shortening velocity was 0.014 ± 0.002 cell lengths/s compared with 0.036 ± 0.002 for the antrum cells. Unloaded shortening velocity in these cells was significantly correlated with their percent SMB expression (r² = 0.58). Resting cell length does not correlate with the percent SMB expression (n = 32 cells). Previously published assays of purified or expressed SMA and SMB heavy meromyosin show a twofold difference in actin filament sliding speed in in vitro motility assays. Extrapolation of our data to 0-100% SMB would give a 10-fold range of shortening velocity, which is closer to the ~20-fold range reported from various SM tissues. This suggests that mechanisms in addition to the MHC S1 head isoforms regulate shortening velocity.

Comments

Accepted version. American Journal of Physiology - Cell Physiology, Volume 280 (February 2001): C309-C316. DOI. © 2001 American Physiological Society. Used with permission.

Recommended Citation

Eddinger, Thomas J. and Meer, Daniel P., "Single Rabbit Stomach Smooth Muscle Cell Myosin Heavy Chain SMB Expression and Shortening Velocity" (2001). Biological Sciences Faculty Research and Publications. 48.
https://epublications.marquette.edu/bio_fac/48