title: Combined blockade of endothelin-1 and thromboxane A(2) receptors against postischaemic contractile dysfunction in rat hearts.
abstract: 1. Endothelin-1 (ET-1) may play a role in myocardial ischaemia/reperfusion injury because both the release and vasoconstrictor effect of ET-1 are increased after ischaemia. Since the increased vasoconstrictor effect of ET-1 can be mediated by ET-1-induced release of thromboxane A(2) (TXA(2)), the aim of this study was to test whether combined blockade of ET and TXA(2) receptors protects the coronary flow, contractile performance, and cardiac energy metabolism during ischaemia and reperfusion. 2. Bosentan (antagonist for ET(A) and ET(B) receptors, 1 microM based on concentration-response curves of ET-1), SQ 30,741 (antagonist of TXA(2) receptors, 0.1 microM), or the combination thereof was administered to isolated perfused rat hearts undergoing 15 min of global ischaemia and 60 min of reperfusion. 3. Neither bosentan or SQ 30,741 alone, nor the combination thereof, improved the incomplete postischaemic recovery of coronary flow, left ventricular developed pressure, phosphocreatine, or ATP. However, they attenuated ischaemia-induced acidosis but this did not translate into a measurable effect on haemodynamic or metabolic variables. 4. Thus, combined blockade of ET and TXA(2) receptors does not protect the coronary flow, contractile performance, and cardiac energy metabolism during ischaemia and reperfusion in isolated perfused rat hearts. This finding suggests that neither ET-1 nor ET-1-induced release of TXA(2) play a major role in the postischaemic recovery of the cardiac contractile function and energy metabolism.
authors.affiliation: Cardiovascular Research Group, Department of Research, ZLF 319, Hebelstrasse 20, University Hospital, CH-4031 Basel, Switzerland. Biology Research Laboratory, NOVARTIS Ltd., H-4002 Basel, Switzerland.
authors.forename: P S
authors.initials: PS
authors.lastname: Hornstein
authors.forename: C E
authors.initials: CE
authors.lastname: Zaugg
authors.forename: P
authors.initials: P
authors.lastname: Zhu
authors.forename: P R
authors.initials: PR
authors.lastname: Allegrini
authors.forename: P T
authors.initials: PT
authors.lastname: Buser
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D000077300:Bosentan; D003326:Coronary Circulation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D065128:Endothelin Receptor Antagonists; D066298:In Vitro Techniques; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D015428:Myocardial Reperfusion Injury / Q000503:physiopathology / Q000517:prevention & control*; D009206:Myocardium / Q000378:metabolism; D010725:Phosphocreatine / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D044022:Receptor, Endothelin A; D017482:Receptors, Thromboxane / Q000037:antagonists & inhibitors*; D013449:Sulfonamides / Q000494:pharmacology; D013928:Thromboxane A2 / Q000031:analogs & derivatives / Q000494:pharmacology; D016277:Ventricular Function, Left / Q000187:drug effects; D017725:Ventricular Pressure / Q000187:drug effects
chemical_list: D065128:Endothelin Receptor Antagonists; D044022:Receptor, Endothelin A; D017482:Receptors, Thromboxane; D013449:Sulfonamides; D010725:Phosphocreatine; C054215:SQ 30741; D013928:Thromboxane A2; D000255:Adenosine Triphosphate; D000077300:Bosentan