Length Dependence of Tension Generation in Rat Skinned Cardiac Muscle

• DOI: 10.1161/hc3901.095898
• Publication Date: 2007-09-28T18:31:09Z
• Authors: Norio Fukuda; Daisuke Sasaki; Shin’ichi Ishiwata; Satoshi Kurihara
• Keywords: Cardiac muscle; Myofilament

At the basis of Frank-Starling mechanism is intrinsic ability cardiac muscle to produce active tension in response stretch. Titin, a giant filamentous molecule involved passive development, intimately associated with thick filament sarcomere. Titin may therefore contribute development by modulating structure when elongated.Rat skinned right ventricular trabeculae were used. Passive at sarcomere length (SL) 2.0 2.4 micrometer was decreased after treatment preparation trypsin (0.25 microgram/mL) for 13 minutes relaxed state 20 degrees C. This mild degraded titin without affecting other major contractile proteins. The little affected brief contractions trypsin-treated preparations. When SL adjusted slack (1.9 micrometer), unaffected under partial (pCa 5.55) and maximal 4.8) activation. longer SLs, however, significantly (P<0.01) either pCa. increase on reduction interfilament lattice spacing, produced dextran T-500 (molecular weight approximately 500 000), not influenced (SL 1.9 micrometer). In preparations, as function diameter nearly same lengthening osmotic compression SL.The length-dependent activation muscle, an underlying law heart, myofilament level, predominantly modulated spacing changes.