title: The effect of 2,5-di-(tert-butyl)-1,4-benzohydroquinone (TBQ) on intracellular Ca2+ handling in rat ventricular myocytes.
abstract: 2,5-Di-(tert-butyl)-1,4-benzohydroquinone (TBQ) is a reversible inhibitor of SERCA, potentially making it a useful tool to study the effects of SERCA inhibition in cardiac cells. However, it is unknown if TBQ also has effects on other components of ventricular Ca handling. The aim of these experiments was to characterise the effects of TBQ on Ca handling in rat ventricular myocytes and assess its suitability as a specific inhibitor of SERCA. This was achieved by voltage clamp via perforated patch and [Ca(2+)]i measurement using Fluo-3 AM. TBQ produced a fully reversible, concentration dependent decrease in the rate of systolic Ca decay. 10μM TBQ decreased the amplitude of the systolic Ca transient by 48±5% and the rate of decay by 54±6%. SR Ca content was also reduced by 62±4%. However, 10μM TBQ also decreased the peak L-type Ca current by 23±7%. At higher concentrations (100μM), TBQ also activated an outward current with a current-voltage relationship consistent with a potassium current. This outward current was abolished by Glibenclamide (100μM). These data show that TBQ can be used to reversibly inhibit SERCA. However, at concentrations that decrease SERCA activity, TBQ also decreases the L-type Ca current and (at higher concentrations) activates an outward current which appears to be an ATP dependent potassium current. We conclude that TBQ cannot be used as a specific inhibitor of SERCA in rat ventricular myocytes.
authors.affiliation: Unit of Cardiac Physiology, Institute of Cardiovascular Sciences, 3.06 Core Technology Facility, 46 Grafton Street, Manchester M13 9NT, United Kingdom.
authors.forename: L
authors.initials: L
authors.lastname: Miller
authors.affiliation: Biomedical Research Centre, School of Environment and Life Sciences, University of Salford, G.35 Peel Building, Salford M5 4WT, United Kingdom. Electronic address: d.j.greensmith@salford.ac.uk.
authors.forename: D J
authors.initials: DJ
authors.lastname: Greensmith
authors.affiliation: Unit of Cardiac Physiology, Institute of Cardiovascular Sciences, 3.06 Core Technology Facility, 46 Grafton Street, Manchester M13 9NT, United Kingdom.
authors.forename: R
authors.initials: R
authors.lastname: Sankaranarayanan
authors.affiliation: Unit of Cardiac Physiology, Institute of Cardiovascular Sciences, 3.06 Core Technology Facility, 46 Grafton Street, Manchester M13 9NT, United Kingdom.
authors.forename: S C
authors.initials: SC
authors.lastname: O'Neill
authors.affiliation: Unit of Cardiac Physiology, Institute of Cardiovascular Sciences, 3.06 Core Technology Facility, 46 Grafton Street, Manchester M13 9NT, United Kingdom.
authors.forename: D A
authors.initials: DA
authors.lastname: Eisner
mesh_terms: D000818:Animals; D016227:Benzoquinones / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D020746:Calcium Channels, L-Type / Q000378:metabolism; D002478:Cells, Cultured; D006352:Heart Ventricles / Q000166:cytology*; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism; D019284:Thapsigargin / Q000494:pharmacology
chemical_list: D016227:Benzoquinones; D020746:Calcium Channels, L-Type; C067344:2,5-di-tert-butylbenzoquinone; D019284:Thapsigargin; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D002118:Calcium
keywords: Calcium; Myocyte; SERCA; TBQ