Display Settings:

Format

Send to:

Choose Destination
J Physiol. 2003 Nov 15;553(Pt 1):147-54. Epub 2003 Sep 8.

Titin isoform variance and length dependence of activation in skinned bovine cardiac muscle.

Author information

  • 1Department of Veterinary and Comparative Anatomy, Pharmacology and Physiology, Washington State University, Pullman, WA 99164-6520, USA.

Abstract

We have explored the role of the giant elastic protein titin in the Frank-Starling mechanism of the heart by measuring the sarcomere length (SL) dependence of activation in skinned cardiac muscles with different titin-based passive stiffness characteristics. We studied muscle from the bovine left ventricle (BLV), which expresses a high level of a stiff titin isoform, and muscle from the bovine left atrium (BLA), which expresses more compliant titin isoforms. Passive tension was also varied in each muscle type by manipulating the pre-history of stretch prior to activation. We found that the SL-dependent increases in Ca2+ sensitivity and maximal Ca2+-activated tension were markedly more pronounced when titin-based passive tension was high. Small-angle X-ray diffraction experiments revealed that the SL dependence of reduction of interfilament lattice spacing is greater in BLV than in BLA and that the lattice spacing is coupled with titin-based passive tension. These results support the notion that titin-based passive tension promotes actomyosin interaction by reducing the lattice spacing. This work indicates that titin may be a factor involved in the Frank-Starling mechanism of the heart by promoting actomyosin interaction in response to stretch.

PMID:
12963792
[PubMed - indexed for MEDLINE]
PMCID:
PMC2343481
Free PMC Article

Images from this publication.See all images (6)Free text

Figure 1
Figure 6
Figure 2
Figure 3
Figure 4
Figure 5
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Icon for HighWire Icon for PubMed Central
    Loading ...
    Write to the Help Desk