Phosphodiesterase types 3 and 4 regulate the phasic contraction of neonatal rat bladder smooth myocytes via distinct mechanisms |
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| Institution: | 1. National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China;2. Inserm UMR-S 769, LabEx LERMIT, F-92296 Châtenay-Malabry, France;3. Université Paris-Sud, Faculté de Pharmacie, F-92296 Châtenay-Malabry, France;4. Institute for Medical Biology, College of Life Sciences, South-Central University for Nationalities, Wuhan, China;2. The James Buchanan Brady Urological Institute, Department of Urology, Johns Hopkins Medical Institutions, Baltimore, MD, USA;3. Urological Research Institute, San Raffaele Scientific Institution, Milan, Italy;4. Laboratory for Experimental Gynecology, Department of Development and Regeneration, University of Leuven, Leuven, Belgium;2. Departamento de Anatomía y Anatomía Patológica Comparadas, Facultad de Veterinaria, Universidad Complutense, Madrid, Spain;1. Department of Pharmacology, Rajendra Institute of Technology and Sciences (RITS), Sirsa 125 055, India;2. Pharmacology Unit, Faculty of Pharmacy, AIMST University, 08100 Bedong, Malaysia |
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| Abstract: | Activation of the cyclic AMP (cAMP) pathway reduces bladder contractility. However, the role of phosphodiesterase (PDE) families in regulating this function is poorly understood. Here, we compared the contractile function of the cAMP hydrolyzing PDEs in neonatal rat bladder smooth myocytes. RT-PCR and Western blotting analysis revealed that several isoforms of PDE1–4 were expressed in neonatal rat bladder. While 8-methoxymethyl-3-isobutyl-1-methylxanthine (a PDE1 inhibitor) and BAY-60-7550 (a PDE2 inhibitor) had no effect on the carbachol-enhanced phasic contractions of bladder strips, cilostamide (Cil, a PDE3 inhibitor) and Ro-20-1724 (Ro, a PDE4 inhibitor) significantly reduced these contractions. This inhibitory effect of Ro was blunted by the PKA inhibitor H-89, while the inhibitory effect of Cil was strongly attenuated by the PKG inhibitor KT 5823. Application of Ro in single bladder smooth myocytes resulted in an increase in Ca2 + spark frequency but a decrease both in Ca2 + transients and in sarcoplasmic reticulum (SR) Ca2 + content. In contrast, Cil had no effect on these events. Furthermore, Ro-induced inhibition of the phasic contractions was significantly blocked by ryanodine and iberiotoxin. Taken together, PDE3 and PDE4 are the main PDE isoforms in maintaining the phasic contractions of bladder smooth myocytes, with PDE4 being functionally more active than PDE3. However, their roles are mediated through different mechanisms. |
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