The effects of vascular smooth muscle caldesmon on force production by 'desensitised' skeletal muscle fibres.
Smooth muscle caldesmon inhibits actomyosin MgATPase in the absence of Ca2+ and is the key regulatory component of Ca2+-regulated thin filaments. We now show that caldesmon can affect contractility as well. Glycerinated skeletal muscle fibres were treated so as to produce substantial contractions without Ca2+ as an activator. Addition of caldesmon caused reductions in force in a concentration- and time-dependent manner. Perfusion with caldesmon concentration for less than 5 min gave up to 48% reduction in isometric tension with a half-maximal effect at 1.5 micron caldesmon. Perfusion with 15 microM caldesmon for 30 min gave an irreversible tension drop.
Taggart
M J
MJ
National Heart and Lung Institute, London, England.
Marston
S B
SB
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002148:Calmodulin-Binding Proteins / Q000494:pharmacology*; D004533:Egtazic Acid / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D007537:Isometric Contraction / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000032:analysis*; D009132:Muscles / Q000502:physiology*; D011817:Rabbits; D012756:Sheep
D002148:Calmodulin-Binding Proteins; D004533:Egtazic Acid; D002118:Calcium