The soluble guanylate cyclase stimulator riociguat and the soluble guanylate cyclase activator cinaciguat exert no direct effects on contractility and relaxation of cardiac myocytes from normal rats.

Abstract

In cardiovascular diseases, reduced responsiveness of soluble guanylate cyclase (sGC) to nitric oxide (NO) upon long-term application has led to the development of NO-independent sGC stimulators (heme-dependent) and sGC activators (heme-independent). Any direct inotropic or lusitropic effects of these compounds on isolated cardiac myocytes, however, remain to be elucidated. Here, we analyzed the dose-dependent effects of clinical relevant concentrations (10(-10)-10(-5) M) of the sGC activator cinaciguat and the sGC stimulator riociguat on the contraction, relaxation, and calcium transients of isolated field-stimulated cardiac myocytes from healthy rats. For comparison, we used isoproterenol, which induced a dose-dependent significant increase in cell contractility, relaxation, and calcium transients, verapamil that significantly decreased these parameters (both at 10(-9)-10(-5) M) and 8-(4-Chlorophenylthio)-guanosine 3',5'-cyclic monophosphate (8-pCPT-cGMP) that induced a negative inotropic effect at 10(-5) M accompanied by a slight increase in relaxation. In contrast, neither cinaciguat nor riociguat significantly influenced any measured parameters. Furthermore, isoproterenol significantly increased intracellular cAMP levels that were not influenced by cinaciguat or riociguat (all at 10(-6) M). Otherwise, riociguat and cinaciguat (both at 10(-6) M) significantly enhanced intracellular cGMP generation. This accumulation was significantly augmented by cinaciguat in the presence of the sGC inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, 25 µM), whereas ODQ blocked cGMP generation by riociguat. However, blocking of sGC did not influence cell contractility. Our results demonstrate that, in isolated cardiac myocytes from healthy rats, the increase in cGMP levels induced by cinaciguat and riociguat at clinical relevant concentrations is not associated with acute direct effects on cell contraction and relaxation.

• Authors: Yvonne Reinke, Stefan Gross, Lars G Eckerle, Isabel Hertrich, Mathias Busch, Raila Busch, Alexander Riad, Bernhard H Rauch, Johannes-Peter Stasch, Marcus Dörr, Stephan B Felix
• Journal: European journal of pharmacology (Eur J Pharmacol) Vol. 767 Pg. 1-9 (Nov 15 2015) ISSN: 1879-0712 [Electronic] Netherlands
• PMID: 26407652 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2015 Elsevier B.V. All rights reserved.

Chemical References

• 1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one
• Benzoates
• Oxadiazoles
• Pyrazoles
• Pyrimidines
• Quinoxalines
• Receptors, Cytoplasmic and Nuclear
• Thionucleotides
• BAY 58-2667
• 8-((4-chlorophenyl)thio)cyclic-3',5'-GMP
• Verapamil
• Cyclic AMP
• Guanylate Cyclase
• Soluble Guanylyl Cyclase
• Cyclic GMP
• Isoproterenol
• riociguat
• Calcium

Topics

• Animals
• Benzoates (agonists, pharmacology)
• Calcium (metabolism)
• Cyclic AMP (metabolism)
• Cyclic GMP (analogs & derivatives, metabolism, pharmacology)
• Dose-Response Relationship, Drug
• Drug Synergism
• Electric Stimulation
• Female
• Guanylate Cyclase
• Isoproterenol (pharmacology)
• Muscle Relaxation (drug effects)
• Myocardial Contraction (drug effects)
• Myocytes, Cardiac (drug effects, metabolism)
• Oxadiazoles (pharmacology)
• Pyrazoles (antagonists & inhibitors, pharmacology)
• Pyrimidines (antagonists & inhibitors, pharmacology)
• Quinoxalines (pharmacology)
• Rats
• Receptors, Cytoplasmic and Nuclear (agonists)
• Soluble Guanylyl Cyclase
• Thionucleotides (pharmacology)
• Verapamil (pharmacology)