Investigation on the positive chronotropic action of 6-nitrodopamine in the rat isolated atria

Author(s)

Britto-Junior, Jose ; Lima, Antonio Tiago ; Fuguhara, Vivian ; Monica, Fabiola Z. Z. ; Antunes, Edson ; De Nucci, Gilberto

• Document type: Journal article
• Source: NAUNYN-SCHMIEDEBERGS ARCHIVES OF PHARMACOLOGY; v. N/A, p. 12-pg., 2023-01-31.

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 mu M, 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 mu M, 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. (AU)

• FAPESP's process: 19/16805-4 - Evaluation of the pathophysiological role of endothelial catecholamines
• Grantee: Gilberto de Nucci
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 17/15175-1 - Modulation of soluble guanylate cyclase and the intracellular levels of cyclic nucleotides in the lower urinary tract and prostate
• Grantee: Edson Antunes
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 21/13593-6 - Evaluation of chronic 6-nitrodopamine treatment in rats
• Grantee: Antonio Tiago Silva Lima
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• FAPESP's process: 21/14414-8 - Evaluation of the action of nitro-catecholamines in the cardiovascular system
• Grantee: José Britto Júnior
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 22/07737-8 - Evaluation of the cardiovascular effect of 6-nitrodopamine in isolated atrium and perfused rat heart
• Grantee: Vivian Fuguhara de Lima
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)