Extracellular cAMP elicits contraction of rat vas deferens: Involvement of ecto-5′-nucleotidase and adenosine A1 receptors

Author(s)

Pacini, Enio Setsuo Arakaki ; Moro, Raissa de Paula ; Godinho, Rosely Oliveira

• Document type: Journal article
• Source: Toxicology and Applied Pharmacology; v. 491, p. 9-pg., 2024-08-20.

Abstract

Aims: It is well established that intracellular cAMP contributes to the relaxation of vas deferens smooth muscle. In many tissues, intracellular cAMP is actively transported to the extracellular space, where it exerts regulatory functions, via its metabolite adenosine. These actions take place through the cAMP conversion to adenosine by ectoenzymes, a process called "extracellular cAMP-adenosine pathway". Herein, we investigated whether, in addition to ATP, extracellular cAMP might be an alternative source of adenosine, influencing the contraction of vas deferens smooth muscle. Main methods: The effects of cAMP, 8-Br-cAMP and adenosine were analyzed in the isometric contractions of rat vas deferens. cAMP efflux was analyzed by measuring extracellular cAMP levels after exposure of vas deferens segments to isoproterenol and forskolin in the presence or absence of MK-571, an inhibitor of MRP/ABCC transporters. Key findings: While 8-Br-cAMP, a cell-permeable cAMP analog, induced relaxation of KCl-precontracted vas deferens, the non-permeant cAMP increased the KCl-induced contractile response, which was mimicked by adenosine, but prevented by inhibitors of ecto-5 '-nucleotidase or A1 receptors. Our results also showed that isoproterenol and forskolin increases cAMP efflux via an MRP/ABCC transporter-dependent mechanism, since it is inhibited by MK-571. Significance: Our data show that activation of beta-adrenoceptors and adenylyl cyclase increases cAMP efflux from vas deferens tissue, which modulates the vas deferens contractile response via activation of adenosine A1 receptors. Assuming that inhibition of vas deferens contractility has been proposed as a strategy for male contraception, the extracellular cAMP-adenosine pathway emerges as a potential pharmacological target that should be considered in studies of male fertility. (AU)

• FAPESP's process: 23/03689-1 - Impact of the extracellular cAMP-adenosine pathway on cAMP signaling
• Grantee: Rosely Oliveira Godinho
• Support Opportunities: Regular Research Grants
• FAPESP's process: 15/06627-0 - Contribution of the extracellular cAMP-adenosine on the contraction of vascular and non-vascular smooth muscle
• Grantee: Raíssa de Paula Moro
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• FAPESP's process: 18/21381-6 - Validation of the "Extracellular cyclic AMP-Adenosine pathway" as a therapeutic target for chronic respiratory diseases.
• Grantee: Rosely Oliveira Godinho
• Support Opportunities: Regular Research Grants