Dataset Information

Atropine augments cardiac contractility by inhibiting cAMP-specific phosphodiesterase type 4.

ABSTRACT: Atropine is a clinically relevant anticholinergic drug, which blocks inhibitory effects of the parasympathetic neurotransmitter acetylcholine on heart rate leading to tachycardia. However, many cardiac effects of atropine cannot be adequately explained solely by its antagonism at muscarinic receptors. In isolated mouse ventricular cardiomyocytes expressing a Förster resonance energy transfer (FRET)-based cAMP biosensor, we confirmed that atropine inhibited acetylcholine-induced decreases in cAMP. Unexpectedly, even in the absence of acetylcholine, after G-protein inactivation with pertussis toxin or in myocytes from M₂- or M_1/3-muscarinic receptor knockout mice, atropine increased cAMP levels that were pre-elevated with the ?-adrenergic agonist isoproterenol. Using the FRET approach and in vitro phosphodiesterase (PDE) activity assays, we show that atropine acts as an allosteric PDE type 4 (PDE4) inhibitor. In human atrial myocardium and in both intact wildtype and M₂ or M_1/3-receptor knockout mouse Langendorff hearts, atropine led to increased contractility and heart rates, respectively. In vivo, the atropine-dependent prolongation of heart rate increase was blunted in PDE4D but not in wildtype or PDE4B knockout mice. We propose that inhibition of PDE4 by atropine accounts, at least in part, for the induction of tachycardia and the arrhythmogenic potency of this drug.

SUBMITTER: Perera RK

PROVIDER: S-EPMC5680190 | biostudies-literature | 2017 Nov

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Atropine augments cardiac contractility by inhibiting cAMP-specific phosphodiesterase type 4.

Perera Ruwan K RK Fischer Thomas H TH Wagner Michael M Dewenter Matthias M Vettel Christiane C Bork Nadja I NI Maier Lars S LS Conti Marco M Wess Juergen J El-Armouche Ali A Hasenfuß Gerd G Nikolaev Viacheslav O VO

Scientific reports 20171109 1

Atropine is a clinically relevant anticholinergic drug, which blocks inhibitory effects of the parasympathetic neurotransmitter acetylcholine on heart rate leading to tachycardia. However, many cardiac effects of atropine cannot be adequately explained solely by its antagonism at muscarinic receptors. In isolated mouse ventricular cardiomyocytes expressing a Förster resonance energy transfer (FRET)-based cAMP biosensor, we confirmed that atropine inhibited acetylcholine-induced decreases in cAMP ...[more]

PMID: 29123207

Similar Datasets

Project description:Cyclic nucleotide phosphodiesterases (PDEs) hydrolyze the intracellular second messengers: cyclic adenosine monophosphate (cAMP) and cyclic guanine monophosphate (cGMP). The cAMP-specific PDE family 4 (PDE4) is widely expressed in vertebrates. Each of the four PDE4 gene isoforms (PDE4 A-D) undergo extensive alternative splicing via alternative transcription initiation sites, producing unique amino termini and yielding multiple splice variant forms from each gene isoform termed long, short, super-short and truncated super-short. Many species across the vertebrate lineage contain multiple splice variants of each gene type, which are characterized by length and amino termini.A phylogenetic approach was used to visualize splice variant form genesis and identify conserved splice variants (genome conservation with EST support) across the vertebrate taxa. Bayesian and maximum likelihood phylogenetic inference indicated PDE4 gene duplication occurred at the base of the vertebrate lineage and reveals additional gene duplications specific to the teleost lineage. Phylogenetic inference and PDE4 splice variant presence, or absence as determined by EST screens, were further supported by the genomic analysis of select vertebrate taxa. Two conserved PDE4 long form splice variants were found in each of the PDE4A, PDE4B, and PDE4C genes, and eight conserved long forms from the PDE4 D gene. Conserved short and super-short splice variants were found from each of the PDE4A, PDE4B, and PDE4 D genes, while truncated super-short variants were found from the PDE4C and PDE4 D genes. PDE4 long form splice variants were found in all taxa sampled (invertebrate through mammals); short, super-short, and truncated super-short are detected primarily in tetrapods and mammals, indicating an increasing complexity in both alternative splicing and cAMP metabolism through vertebrate evolution.There was a progressive independent incorporation of multiple PDE4 splice variant forms and amino termini, increasing PDE4 proteome complexity from primitive vertebrates to humans. While PDE4 gene isoform duplicates with limited alternative splicing were found in teleosts, an expansion of both PDE4 splice variant forms, and alternatively spliced amino termini predominantly occurs in mammals. Since amino termini have been linked to intracellular targeting of the PDE4 enzymes, the conservation of amino termini in PDE4 splice variants in evolution highlights the importance of compartmentalization of PDE4-mediated cAMP hydrolysis.

Project description:Trypanosoma cruzi, the causative agent of Chagas disease, encodes a number of different cAMP-specific PDE (phosphodiesterase) families. Here we report the identification and characterization of TcrPDEB1 and its comparison with the previously identified TcrPDEB2 (formerly known as TcPDE1). These are two different PDE enzymes of the TcrPDEB family, named in accordance with the recent recommendations of the Nomenclature Committee for Kinetoplast PDEs [Kunz, Beavo, D'Angelo, Flawia, Francis, Johner, Laxman, Oberholzer, Rascon, Shakur et al. (2006) Mol. Biochem. Parasitol. 145, 133-135]. Both enzymes show resistance to inhibition by many mammalian PDE inhibitors, and those that do inhibit do so with appreciable differences in their inhibitor profiles for the two enzymes. Both enzymes contain two GAF (cGMP-specific and -stimulated phosphodiesterases, Anabaena adenylate cyclases and Escherichia coli FhlA) domains and a catalytic domain highly homologous with that of the T. brucei TbPDE2/TbrPDEB2 family. The N-terminus+GAF-A domains of both enzymes showed significant differences in their affinities for cyclic nucleotide binding. Using a calorimetric technique that allows accurate measurements of low-affinity binding sites, the TcrPDEB2 N-terminus+GAF-A domain was found to bind cAMP with an affinity of approximately 500 nM. The TcrPDEB1 N-terminus+GAF-A domain bound cAMP with a slightly lower affinity of approximately 1 muM. The N-terminus+GAF-A domain of TcrPDEB1 did not bind cGMP, whereas the N-terminus+GAF-A domain of TcrPDEB2 bound cGMP with a low affinity of approximately 3 muM. GAF domains homologous with those found in these proteins were also identified in related trypanosomatid parasites. Finally, a fluorescent cAMP analogue, MANT-cAMP [2'-O-(N-methylanthraniloyl)adenosine-3',5'-cyclic monophosphate], was found to be a substrate for the TcPDEB1 catalytic domain, opening the possibility of using this molecule as a substrate in non-radioactive, fluorescence-based PDE assays, including screening for trypanosome PDE inhibitors.

Dataset Information

Atropine augments cardiac contractility by inhibiting cAMP-specific phosphodiesterase type 4.

Publications

Atropine augments cardiac contractility by inhibiting cAMP-specific phosphodiesterase type 4.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets