4-Nitro-propranolol selectively inhibits the positive chronotropic effect induced by 6-nitrodopamine in the rat isolated right atrium DOI Creative Commons

Denis Lima Oliveira,

Vinicius Francisco Cardoso,

José Britto‐Júnior

et al.

Research Square (Research Square), Journal Year: 2023, Volume and Issue: unknown

Published: Oct. 27, 2023

Abstract 6-Nitrodopamine (6-ND) is released from isolated atria of rabbit, rat and mice has significant positive chronotropic action. The effect induced by 6-ND selectively blocked β1-adrenoceptor antagonists at concentrations that do not affect the dopamine, noradrenaline, adrenaline. Here effects propranolol, 4-NO2-propranolol 7-NO2-propranolol were investigated in right atrium. atrium was mounted between two metal hooks 10-mL custom designed glass chambers containing Krebs-Henseleit’s solution, continuously gassed (95%O2:5%CO2) heated (37°C). Tissues allowed to equilibrate under a resting tension 10 mN for one hour, isometric registered using PowerLab system. 4-NO2-propranol more potent than propranolol as negative agent. At 30 nM, did S-isomer 4- NO2-propranolol, but R-isomer, active. Propranolol fall atrial rate higher those required block noradrenaline adrenaline, enough effect. only active very high concentration, stereoselective. (100 nM) (300 observed L-NAME treated atria, whereas (10 mM) unaffected. selective inhibition with (±)-4-NO2-propranolol reinforces concept major mediator heart chronotropism main target so-called b-blockers.

Language: Английский

4-Nitro-propranolol selectively inhibits the positive chronotropic effect induced by 6-nitrodopamine in the rat isolated right atrium DOI Creative Commons

Denis Lima Oliveira,

Vinicius Francisco Cardoso,

José Britto‐Júnior

et al.

Research Square (Research Square), Journal Year: 2023, Volume and Issue: unknown

Published: Oct. 27, 2023

Abstract 6-Nitrodopamine (6-ND) is released from isolated atria of rabbit, rat and mice has significant positive chronotropic action. The effect induced by 6-ND selectively blocked β1-adrenoceptor antagonists at concentrations that do not affect the dopamine, noradrenaline, adrenaline. Here effects propranolol, 4-NO2-propranolol 7-NO2-propranolol were investigated in right atrium. atrium was mounted between two metal hooks 10-mL custom designed glass chambers containing Krebs-Henseleit’s solution, continuously gassed (95%O2:5%CO2) heated (37°C). Tissues allowed to equilibrate under a resting tension 10 mN for one hour, isometric registered using PowerLab system. 4-NO2-propranol more potent than propranolol as negative agent. At 30 nM, did S-isomer 4- NO2-propranolol, but R-isomer, active. Propranolol fall atrial rate higher those required block noradrenaline adrenaline, enough effect. only active very high concentration, stereoselective. (100 nM) (300 observed L-NAME treated atria, whereas (10 mM) unaffected. selective inhibition with (±)-4-NO2-propranolol reinforces concept major mediator heart chronotropism main target so-called b-blockers.

Language: Английский

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