title: Blebbistatin: use as inhibitor of muscle contraction.
abstract: Blebbistatin (BLEB) is a recently discovered compound that inhibits myosin-II ATPase activity. In this study, we tested BLEB in intact and skinned isolated rat cardiac trabeculae, rat intact myocytes, and single rabbit psoas myofibrils. BLEB (10 muM) reduced twitch force and cell shortening that was reversed by exposure to light. BLEB treatment of skinned trabeculae in the dark (1 hr) reduced Ca(2+)-activated force (EC(50) = 0.38 +/- 0.03 muM). Rapid (<5 ms) BLEB application in Ca(2+)-activated rabbit myofibrils reduced force proportional to [BLEB]. Two-photon Indo1-AM ratio-metric confocal line-scan microscopy revealed no impact of BLEB on the cytosolic Ca(2+) transient. BLEB reduced contractile force in skinned trabeculae without affecting tension-dependent myofilament ATPase activity. We conclude that BLEB specifically uncouples cardiac myofilament activation from Ca(2+) activation without affecting EC coupling or cross-bridge cycling parameters. This agent could be useful to uncouple myofilament contractility from electrical events that lead to sarcoplasmic reticulum Ca(2+) release in the cardiac myocyte (uncoupling agent) However, the compound is very sensitive to light, a property that limits its application to mechanistic physiological studies.
authors.affiliation: Center for Cardiovascular Research, Department of Physiology and Biophysics M/C 901, University of Illinois at Chicago, College of Medicine Chicago, Chicago, IL 60612-7342, USA.
authors.forename: Gerrie P
authors.initials: GP
authors.lastname: Farman
authors.forename: Kittipong
authors.initials: K
authors.lastname: Tachampa
authors.forename: Ryan
authors.initials: R
authors.lastname: Mateja
authors.forename: Olivier
authors.initials: O
authors.lastname: Cazorla
authors.forename: Alain
authors.initials: A
authors.lastname: Lacampagne
authors.forename: Pieter P
authors.initials: PP
authors.lastname: de Tombe
mesh_terms: D008841:Actin Cytoskeleton / Q000201:enzymology / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000814:Aniline Compounds; D000818:Animals; D020013:Calcium Signaling / Q000187:drug effects; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D003627:Data Interpretation, Statistical; D003931:Diacetyl / Q000031:analogs & derivatives / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005456:Fluorescent Dyes; D006576:Heterocyclic Compounds, 4 or More Rings / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D018613:Microscopy, Confocal; D009119:Muscle Contraction / Q000187:drug effects*; D018485:Muscle Fibers, Skeletal / Q000187:drug effects / Q000201:enzymology; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000201:enzymology; D051381:Rats; D014966:Xanthenes
chemical_list: D000814:Aniline Compounds; D004791:Enzyme Inhibitors; C409648:Fluo 4; D005456:Fluorescent Dyes; D006576:Heterocyclic Compounds, 4 or More Rings; D014966:Xanthenes; C004717:diacetylmonoxime; C472645:blebbistatin; D000251:Adenosine Triphosphatases; D003931:Diacetyl