Carly J McCarthy1,2, Youko Ikeda3,2, Deborah Skennerton2, Basu Chakrabarty4, Anthony J Kanai3, Rita I Jabr5, Christopher H Fry2,4. 1. Instituto de Investigaciones en Medicina Traslacional (IIMT), Facultad de Ciencias Biomédicas, Austral University, Buenos Aires, Argentina. 2. Department of Surgery, University College London, London, UK. 3. Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania. 4. School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK. 5. School of Biosciences and Medicine, University of Surrey, Surrey, UK.
Abstract
BACKGROUND AND PURPOSE: This study aims to characterise the molecular mechanisms that determine variability of atropine resistance of nerve-mediated contractions in human and guinea pig detrusor smooth muscle. EXPERIMENTAL APPROACH: Atropine resistance of nerve-mediated contractions and the role of P2X1 receptors, were assessed in isolated preparations from guinea pigs and also humans with or without overactive bladder syndrome, from which the mucosa was removed. Nerve-mediated ATP release was measured directly with amperometric ATP-sensitive electrodes. Ecto-ATPase activity of guinea pig and human detrusor samples was measured in vitro by measuring the concentration-dependent rate of ATP breakdown. The transcription of ecto-ATPase subtypes in human samples was measured by qPCR. KEY RESULTS: Atropine resistance was greatest in guinea pig detrusor, absent in human tissue from normally functioning bladders, and intermediate in human overactive bladder. Greater atropine resistance correlated with reduction of contractions by the ATP-diphosphohydrolase apyrase, directly implicating ATP in their generation. E-NTPDase-1 was the most abundantly transcribed ecto-ATPase of those tested, and transcription was reduced in tissue from human overactive, compared to normal, bladders. E-NTPDase-1 enzymic activity was inversely related to the magnitude of atropine resistance. Nerve-mediated ATP release was continually measured and varied with stimulation frequency over the range of 1-16 Hz. CONCLUSION AND IMPLICATIONS: Atropine resistance in nerve-mediated detrusor contractions is due to ATP release and its magnitude is inversely related to E-NTPDase-1 activity. ATP is released under different stimulation conditions compared with ACh, implying different routes for their release.
BACKGROUND AND PURPOSE: This study aims to characterise the molecular mechanisms that determine variability of atropine resistance of nerve-mediated contractions in human and guinea pig detrusor smooth muscle. EXPERIMENTAL APPROACH: Atropine resistance of nerve-mediated contractions and the role of P2X1 receptors, were assessed in isolated preparations from guinea pigs and also humans with or without overactive bladder syndrome, from which the mucosa was removed. Nerve-mediated ATP release was measured directly with amperometric ATP-sensitive electrodes. Ecto-ATPase activity of guinea pig and human detrusor samples was measured in vitro by measuring the concentration-dependent rate of ATP breakdown. The transcription of ecto-ATPase subtypes in human samples was measured by qPCR. KEY RESULTS:Atropine resistance was greatest in guinea pig detrusor, absent in human tissue from normally functioning bladders, and intermediate in humanoveractive bladder. Greater atropine resistance correlated with reduction of contractions by the ATP-diphosphohydrolase apyrase, directly implicating ATP in their generation. E-NTPDase-1 was the most abundantly transcribed ecto-ATPase of those tested, and transcription was reduced in tissue from human overactive, compared to normal, bladders. E-NTPDase-1 enzymic activity was inversely related to the magnitude of atropine resistance. Nerve-mediated ATP release was continually measured and varied with stimulation frequency over the range of 1-16 Hz. CONCLUSION AND IMPLICATIONS: Atropine resistance in nerve-mediated detrusor contractions is due to ATP release and its magnitude is inversely related to E-NTPDase-1 activity. ATP is released under different stimulation conditions compared with ACh, implying different routes for their release.
Authors: Michael J Curtis; Steve Alexander; Giuseppe Cirino; James R Docherty; Christopher H George; Mark A Giembycz; Daniel Hoyer; Paul A Insel; Angelo A Izzo; Yong Ji; David J MacEwan; Christopher G Sobey; S Clare Stanford; Mauro M Teixeira; Sue Wonnacott; Amrita Ahluwalia Journal: Br J Pharmacol Date: 2018-04 Impact factor: 8.739
Authors: Barry A O'Reilly; Alan H Kosaka; Gillian F Knight; Thomas K Chang; Anthony P D W Ford; Janice M Rymer; Rick Popert; Geoffrey Burnstock; Stephen B McMahon Journal: J Urol Date: 2002-01 Impact factor: 7.450
Authors: Simon D Harding; Joanna L Sharman; Elena Faccenda; Chris Southan; Adam J Pawson; Sam Ireland; Alasdair J G Gray; Liam Bruce; Stephen P H Alexander; Stephen Anderton; Clare Bryant; Anthony P Davenport; Christian Doerig; Doriano Fabbro; Francesca Levi-Schaffer; Michael Spedding; Jamie A Davies Journal: Nucleic Acids Res Date: 2018-01-04 Impact factor: 16.971