Sphingosine 1-phosphate induces sinus tachycardia and coronary vasoconstriction in the canine heart

Objective: Sphingosine 1-phosphate is a naturally occurring biologically active lysophospholipid. Recent studies suggested that sphingosine 1-phosphate is released into the blood flow from activated platelets upon stimulation to exert multiple biological phenomenon. The purpose of this study was to assess the effects of sphingosine 1-phosphate on sinus automaticity, ventricular contraction and coronary blood flow. Methods: The canine isolated, blood-perfused sinoatrial node and papillary muscle preparations were used. Results: Sphingosine 1-phosphate increased the sinoatrial rate, while it decreased the coronary blood flow, which was followed by a weak negative inotropic effect. These positive chronotropic and coronary vasoconstrictor effects were not attenuated by the beta- and alpha-adrenoceptor antagonists atenolol and prazosin, respectively. Furthermore, sphingosine 1-phosphate did not affect the adenylate cyclase activity of the membrane preparations made from the canine right atrium and right ventricle, indicating the involvement of a novel signaling pathway in sphingosine 1-phosphate-induced cardiac effects. Conclusions: These results may provide a clue to better understanding the physiological as well as the pathophysiological regulation of sphingosine 1-phosphate in the heart. (C) 2000 Elsevier Science B.V. All rights reserved.