Abstract
Dopamine (DA), noradrenaline, and adrenaline are known for their sympathomimetic roles. In the heart, the right isolated rat atrium has greater expression of beta-1 adrenoceptors compared to the left atrium of the same animal, making it a source of chronotropism study. 6-nitrodopamine (6-ND) emerges as the main new catecholamine responsible for the positive chronotropic and inotropic effe…