Data/hora: 10/06/2024 18:32:07

Provedor de dados: | 56
País: | Brazil
Título: | Effect of acute nitric oxide synthase inhibition in the modulation of heart rate in rats
Autores: | Fellet,A.L.; Di Verniero,C.; Arza,P.; Tomat,A.; Varela,A.; Arranz,C.; Balaszczuk,A.M.
Data: | 2003-05-01
Ano: | 2003
Palavras-chave: | Nitric oxide; Nitric oxide synthase; Autonomic nervous system; Heart rate; Heart.
Resumo: | Acute nitric oxide synthase inhibition with N G-nitro-L-arginine methyl ester (L-NAME) on chronotropic and pressor responses was studied in anesthetized intact rats and rats submitted to partial and complete autonomic blockade. Blood pressure and heart rate were monitored intra-arterially. Intravenous L-NAME injection (7.5 mg/kg) elicited the same hypertensive response in intact rats and in rats with partial (ganglionic and parasympathetic blockade) and complete autonomic blockade (38 ± 3, 55 ± 6, 54 ± 5, 45 ± 5 mmHg, respectively; N = 9, P = NS). L-NAME-induced bradycardia at the time when blood pressure reached the peak plateau was similar in intact rats and in rats with partial autonomic blockade (43 ± 8, 38 ± 5, 46 ± 6 bpm, respectively; N = 9, P = NS). Rats with combined autonomic blockade showed a tachycardic response to L-NAME (10 ± 3 bpm, P&lt;0.05 vs intact animals, N = 9). Increasing doses of L-NAME (5.0, 7.5 and 10 mg/kg, N = 9) caused a similar increase in blood pressure (45 ± 5, 38 ± 3, 44 ± 9 mmHg, respectively; P = NS) and heart rate (31 ± 4, 34 ± 3, 35 ± 4 bpm, respectively; P = NS). Addition of L-NAME (500 µM) to isolated atria from rats killed by cervical dislocation and rats previously subjected to complete autonomic blockade did not affect spontaneous beating or contractile strength (N = 9). In vivo results showed that L-NAME promoted a tachycardic response in rats with complete autonomic blockade, whereas the in vitro experiments showed no effect on intrinsic heart rate, suggesting that humoral mechanisms may be involved in the L-NAME-induced cardiac response.
Tipo: | Info:eu-repo/semantics/article
Idioma: | Inglês
Identificador: | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2003000500015
Editor: | Associação Brasileira de Divulgação Científica
Relação: | 10.1590/S0100-879X2003000500015
Formato: | text/html
Fonte: | Brazilian Journal of Medical and Biological Research  v.36 n.5 2003
Fonte: | info:eu-repo/semantics/openAccess