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Britto-Júnior J, Lima AT, Fuguhara V, Monica FZ, Antunes E, De Nucci G. Investigation on the positive chronotropic action of 6-nitrodopamine in the rat isolated atria. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2023; 396:1279-1290. [PMID: 36719453 DOI: 10.1007/s00210-023-02394-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2022] [Accepted: 01/10/2023] [Indexed: 02/01/2023]
Abstract
6-Nitrodopamine (6-ND) is released from rat isolated atria being 100 times more potent than noradrenaline and adrenaline, and 10,000 times more potent than dopamine as a positive chronotropic agent. The present study aimed to investigate the interactions of 6-ND with the classical catecholamines, phosphodiesterase (PDE)-3 and PDE4, and the protein kinase A in rat isolated atria. Atrial incubation with 1 pM of dopamine, noradrenaline, or adrenaline had no effect on atrial frequency. Similar results were observed when the atria were incubated with 0.01 pM of 6-ND. However, co-incubation of 6-ND (0.01 pM) with dopamine, noradrenaline, or adrenaline (1 pM each) resulted in significant increases in atrial rate, which persisted over 30 min after washout of the agonists. The increased atrial frequency induced by co-incubation of 6-ND with the catecholamines was significantly reduced by the voltage-gated sodium channel blocker tetrodotoxin (1 µM, 30 min), indicating that the positive chronotropic effect of 6-ND is due in part to activation of nerve terminals. Pre-treatment of the animals with reserpine had no effect on the positive chronotropic effect induced by dopamine, noradrenaline, or adrenaline; however, reserpine markedly reduced the 6-ND (1 pM)-induced positive chronotropic effect. Incubation of the rat isolated atria with the protein kinase A inhibitor H-89 (1 µM, 30 min) abolished the increased atrial frequency induced by dopamine, noradrenaline, and adrenaline, but only attenuated the increases induced by 6-ND. 6-ND induces catecholamine release from adrenergic terminals and increases atrial frequency independently of PKA activation.
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Affiliation(s)
- José Britto-Júnior
- Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Rua Tessália Vieira de Camargo, 126, Cidade Universitária, 13083-887, Campinas, São Paulo, Brazil.
| | - Antonio Tiago Lima
- Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Rua Tessália Vieira de Camargo, 126, Cidade Universitária, 13083-887, Campinas, São Paulo, Brazil
| | - Vivian Fuguhara
- Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Rua Tessália Vieira de Camargo, 126, Cidade Universitária, 13083-887, Campinas, São Paulo, Brazil
| | - Fabiola Z Monica
- Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Rua Tessália Vieira de Camargo, 126, Cidade Universitária, 13083-887, Campinas, São Paulo, Brazil
| | - Edson Antunes
- Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Rua Tessália Vieira de Camargo, 126, Cidade Universitária, 13083-887, Campinas, São Paulo, Brazil
| | - Gilberto De Nucci
- Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Rua Tessália Vieira de Camargo, 126, Cidade Universitária, 13083-887, Campinas, São Paulo, Brazil
- Department of Pharmacology, Faculty of Medicine, São Leopoldo Mandic, Campinas, SP, Brazil
- Department of Pharmacology, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo, SP, Brazil
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Cox SL, Schelb V, Trendelenburg AU, Starke K. Enhancement of noradrenaline release by angiotensin II and bradykinin in mouse atria: evidence for cross-talk between G(q/11) protein- and G(i/o) protein-coupled receptors. Br J Pharmacol 2000; 129:1095-102. [PMID: 10725257 PMCID: PMC1571946 DOI: 10.1038/sj.bjp.0703167] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. The interaction between alpha(2)-autoreceptors and receptors for angiotensin (AT(1)) and bradykinin (B(2)) was studied in mouse isolated atria. The preparations were labelled with [(3)H]-noradrenaline and then superfused with desipramine-containing medium and stimulated electrically. 2. Angiotensin II (10(-11) - 10(-7) M), angiotensin III (10(-10) - 10(-6) M) and bradykinin (10(-11) - 10(-7) M) enhanced the evoked overflow of tritium when preparations were stimulated with conditions that led to marked alpha(2)-autoinhibition (120 pulses at 3 Hz), but not when stimulated with conditions that led to little alpha(2)-autoinhibition (20 pulses at 50 Hz). 3. Blockade of alpha-adrenoceptors by phentolamine (1 or 10 microM) reduced or abolished the effect of angiotensin II and bradykinin on the overflow response to 120 pulses at 3 Hz. 4. Addition of the delta-opioid agonist [D-Ser(2)]-leucine enkephalin-Thr (DSLET, 0.1 microM), or of neuropeptide Y (0.1 microM), together with phentolamine, restored the effect of angiotensin II and bradykinin. 5. The beta-adrenoceptor agonist terbutaline (10(-9) - 10(-4) M) enhanced the evoked overflow of tritium irrespective of the degree of autoinhibition. 6. The experiments show that (i) a marked prejunctional facilitatory effect of angiotensin and bradykinin in mouse isolated atria requires prejunctional alpha(2)-autoinhibition; (ii) in the absence of alpha(2)-autoinhibition, activation of other prejunctional G(i/o) protein-coupled receptors, namely opioid and neuropeptide Y receptors, restores a marked effect of angiotensin II and bradykinin; and (iii) the facilitatory effect of terbutaline is not dependent upon the degree of alpha(2)-autoinhibition. The findings indicate that the major part of the release-enhancing effect elicited through prejunctional G(q/11) protein-coupled receptors is due to disruption of an ongoing, alpha(2)-autoreceptor-triggered G(i/o) protein mediated inhibition.
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Affiliation(s)
- S L Cox
- Pharmakologisches Institut, Universität Freiburg, Hermann-Herder-Strasse 5, D-79104, Freiburg i. Br., Germany.
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Vaughan PF, Walker JH, Peers C. The regulation of neurotransmitter secretion by protein kinase C. Mol Neurobiol 1998; 18:125-55. [PMID: 10065877 DOI: 10.1007/bf02914269] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The effect of protein kinase C (PKC) on the release of neurotransmitters from a number preparations, including sympathetic nerve endings, brain slices, synaptosomes, and neuronally derived cell lines, is considered. A comparison is drawn between effects of activation of PKC on neurotransmitter release from small synaptic vesicles and large dense-cored vesicles. The enhancement of neurotransmitter release is discussed in relation to the effect of PKC on: 1. Rearrangement of the F-actin-based cytoskeleton, including the possible role of MARCKS in this process, to allow access of large dense-cored vesicles to release sites on the plasma membrane. 2. Phosphorylation of key components in the SNAP/SNARE complex associated with the docking and fusion of vesicles at site of secretion. 3. Ion channel activity, particularly Ca2+ channels.
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Affiliation(s)
- P F Vaughan
- Institute for Cardiovascular Research, University of Leeds, UK
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