Intrinsic Adaptation of SHR Right Atrium Reduces Heart Rate

Autor(es)

Dantas Rodrigues, Juliano Quintella ^[1] ; Camara, Henrique ^[1] ; da Silva Junior, Edilson Dantas ^[1] ; Godinho, Rosely Oliveira ^[1] ; Jurkiewicz, Aron ^[1]

Afiliação do(s) autor(es)

^[1] Univ Fed Sao Paulo, UNIFESP, EPM, Dept Pharmacol, Rua Tres Maio 100, 2 Floor, BR-04044020 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Journal of Cardiovascular Pharmacology; v. 74, n. 6, p. 542-548, DEC 2019.
• Citações Web of Science: 0

Resumo

Hypertension represents an autonomic dysfunction, characterized by increased sympathetic and decreased parasympathetic cardiovascular tone leading to resting tachycardia. Therefore, studies assessing hypertension-associated changes in isolated cardiac tissues were conducted under electric field stimulation to stimulate the neurons. Herein, we characterize the influence of the autonomic neurotransmitter on the baseline atrial chronotropism of unpaced isolated right atria of normotensive Wistar rats (NWR) and spontaneously hypertensive rats (SHR). Our results revealed a resting bradycardia in tissues from SHR in comparison to NWR. The release of autonomic neurotransmitters, acetylcholine or norepinephrine, still occurs in the electrically unstimulated right atrium, after excision of the sympathetic nerve, which could explain differences in basal heart rate between NWR and SHR. Nicotine and the acetylcholinesterase inhibitor physostigmine reduced the chronotropism of right atria from either NWR or SHR. Conversely, the muscarinic receptor antagonist atropine did not affect the basal chronotropism of tissues from both strains. Furthermore, tyramine increased the chronotropism of NWR and SHR atria indicating availability of the neuronal stocks of noradrenaline. Although the monoamine uptake inhibitor cocaine increased right atrium chronotropism in both strains, the basal heart rate was not affected by the beta-adrenoceptor antagonist propranolol. In summary, after acute section of the sympathetic nerve, autonomic neurotransmitters are still released either in resting conditions or upon pharmacological stimulation of right atria from both strains. Nevertheless, autonomic neurotransmission does not affect resting chronotropism, nor is the responsible for reduced basal heart rate of the isolated right atrium of hypertensive rats. (AU)

• Processo FAPESP: 12/22763-3 - Estudo funcional, bioquímico e molecular dos Receptores Purinérgicos P1 e P2 em Átrios de Ratos Normotensos e Hipertensos
• Beneficiário: Juliano Quintella Dantas Rodrigues
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 15/07019-4 - Papel da via extracelular AMP cíclico-adenosina na fisiopatologia do sistema respiratório e do sistema neuromuscular esquelético
• Beneficiário: Rosely Oliveira Godinho
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 12/24828-5 - Estudo da modulação da função cardíaca pelos receptores purinérgicos em átrios de ratos Wistar - EPM-1
• Beneficiário: Henrique Camara
• Modalidade de apoio: Bolsas no Brasil - Iniciação Científica