PDE1A inhibition elicits cGMP‐dependent relaxation of rat mesenteric arteries

Abstract

*Contributed equally. BACKGROUND AND PURPOSEPDE1, a subfamily of cyclic nucleotide PDEs consisting of three isoforms, PDE1A, PDE1B and PDE1C, has been implicated in the regulation of vascular tone. The PDE1 isoform(s) responsible for tone regulation is unknown. This study used isoform-preferring PDE1 inhibitors, Lu AF58027, Lu AF64196, Lu AF66896 and Lu AF67897, to investigate the relative contribution of PDE1 isoforms to regulation of vascular tone. EXPERIMENTAL APPROACHIn rat mesenteric arteries, expression and localization of Pde1 isoforms were determined by quantitative PCR and in situ hybridization, and physiological impact of PDE1 inhibition was evaluated by isometric tension recordings. KEY RESULTSIn rat mesenteric arteries, Pde1a mRNA expression was higher than Pde1b and Pde1c. In situ hybridization revealed localization of Pde1a to vascular smooth muscle cells (VSMCs) and only minor appearance of Pde1b and Pde1c. The potency of the PDE1 inhibitors at eliciting relaxation showed excellent correlation with their potency at inhibiting PDE1A. Thus, Lu AF58027 was the most potent at inhibiting PDE1A and was also the most potent at eliciting relaxation in mesenteric arteries. Inhibition of NOS with L-NAME, soluble GC with ODQ or PKG with Rp-8-Br-PET-cGMP all attenuated the inhibitory effect of PDE1 on relaxation, whereas PKA inhibition with H89 had no effect. CONCLUSIONS AND IMPLICATIONSPde1a is the dominant PDE1 isoform present in VSMCs, and relaxation mediated by PDE1A inhibition is predominantly driven by enhanced cGMP signalling. These results imply that isoform-selective PDE1 inhibitors are powerful investigative tools allowing examination of physiological and pathological roles of PDE1 isoforms. AbbreviationsCCh, carbachol; H89, N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide dihydrochloride; ODQ, 1H-[1,2,4] oxadiazolo[4,3-a]quinoxalin-1-one; Rp-8, Rp-8-Br-PET-cGMPS; U46619, 9 α-epoxymethanoPGF 2α ; VSMCs, vascular smooth muscle cells

Selective Phosphodiesterase 1 Inhibitor BTTQ Reduces Blood Pressure in Spontaneously Hypertensive and Dahl Salt Sensitive Rats: Role of Peripheral Vasodilation

“…Since PDE1A is the major isoform expressed in arterial SMC (Giachini et al, 2011;Khammy et al, 2017), it is highly likely that BP lowering activity of BTTQ is primarily driven by its inhibition of PDE1A. The preferred substrate of PDE1A is cGMP that is produced in vascular SMCs by nitric oxide-induced soluble guanylate cyclase or natriuretic peptide-activated particulate guanylate cyclase (Francis et al, 2010).…”

“…The role of PDE5 and PDE3 is widely explored in this context (Turko et al, 1999;Bellamy and Garthwaite, 2001;Corbin, 2004). PDE1 is highly expressed in SMCs (Giachini et al, 2011;Khammy et al, 2017). However, much less attention has been paid to PDE1.…”

Phosphodiesterase 1 Bridges Glutamate Inputs with NO- and Dopamine-Induced Cyclic Nucleotide Signals in the Striatum

“…We then used the selective PDE1 inhibitor Lu AF64196 (Khammy et al, 2017) to determine the contribution of PDE1 on the change in cGMP level induced by NMDA uncaging ( Figure 2C). The addition of 10 µM Lu AF64196 to DEANO had no effect on the steady-state cGMP levels, showing that PDE1 does not control cGMP in that condition.…”

“…Imaging PDE1 action in neurones control of vascular smooth muscle cell relaxation (Khammy et al, 2017).…”

“…In the first part of this work, the experiments were designed to reveal the action of PDE1 on artificially elevated steady-state cyclic nucleotide levels: a transient increase in intracellular calcium triggered by uncaging NMDA transiently reduced both cAMP and cGMP. We used the recently developed selective PDE1 inhibitor, Lu AF64196 (Khammy et al, 2017) to show that this effect was mediated by PDE1. The second part of this work shows a functional inhibitory effect of PDE1 on the transient cAMP response to dopamine and on long term potentiation (LTP).…”