Prolactin-releasing peptide regulates cardiac contractility |
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| Authors: | Attila Kónyi Réka Skoumal Anna-Maria Kubin Gábor Füredi Ábel Perjés Klára Farkasfalvi Zsolt Sárszegi Ferenc Horkay Iván G. Horváth Miklós Tóth Heikki Ruskoaho István Szokodi |
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| Affiliation: | 1. Heart Institute, Medical School, University of Pécs, Pécs, Hungary;2. Institute of Biomedicine, Department of Pharmacology and Toxicology, Biocenter Oulu, University of Oulu, Oulu, Finland;3. Department of Cardiac Surgery, Semmelweis University, Budapest, Hungary;4. Department of Health Sciences and Sports Medicine, Semmelweis University, Budapest, Hungary |
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| Abstract: | High levels of specific prolactin-releasing peptide (PrRP) binding sites have been found in the myocardium; however, the functional importance of PrRP in the regulation of cardiac function is unknown. In isolated perfused rat hearts, infusion of PrRP (1–100 nM) induced a dose-dependent positive inotropic effect. Inhibition of cAMP catabolism by IBMX, a phosphodiesterase inhibitor, failed to augment the contractile effect of PrRP. The protein phosphatase (PP1/PP2A) inhibitor calyculin A increased the inotropic response to PrRP, whereas the PP2A inhibitor okadaic acid had no effect. Ro32-0432, a protein kinase Cα (PKCα) inhibitor, significantly enhanced the inotropic effect of PrRP as well as the phosphorylation of phospholamban at Ser-16. In conclusion, the present data define a hitherto unrecognized role for PrRP in the regulation of cardiovascular system by showing that PrRP exerts a direct positive inotropic effect. Moreover, our results suggest that the cAMP-independent inotropic response to PrRP is suppressed by concurrent activation of PKCα and PP1. |
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