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An inotrope [help 1] or inotropic is a drug or any substance that alters the force or energy of muscular contractions. Negatively inotropic agents weaken the force of muscular contractions. Positively inotropic agents increase the strength of muscular contraction.
Lusitropy or lucitropy is the rate of myocardial relaxation. The increase in cytosolic calcium of cardiomyocytes via increased uptake leads to increased myocardial contractility (positive inotropic effect), but the myocardial relaxation, or lusitropy, decreases.
An ionotropic effect is the effect of a transmitter substance or hormone that activates or deactivates ionotropic receptors (ligand-gated ion channels).The effect can be either positive or negative, specifically a depolarization or a hyperpolarization respectively.
Cardiotonic agents, also known as cardiac inotropes or stimulants, have a positive impact on the myocardium (muscular layer of the heart) by enhancing its contractility. . Unlike general inotropes, these agents exhibit a higher level of specificity as they selectively target the myocar
The effects of amrinone vary widely with species and experimental condition; therefore, its inotropic effects are variable. [3] A loss in sensitivity to phosphodiesterase 3 inhibitors, including amrinone, has been observed in end stage heart failure in humans; other treatment options may be more useful for improvement in these stages. [3]
In 1897 Engelmann introduced four Greek terms to describe key physiological properties of the heart: inotropy, [4] the ability to contract; chronotropy, the ability to initiate an electrical impulse; dromotropy, the ability to conduct an electrical impulse; and bathmotropy, the ability to respond to direct mechanical stimulation.
Chronotropic effects (from chrono-, meaning time, and tropos, "a turn") are those that change the heart rate.. Chronotropic drugs may change the heart rate and rhythm by affecting the electrical conduction system of the heart and the nerves that influence it, such as by changing the rhythm produced by the sinoatrial node.
Pimobendan is a positive inotrope, and its main function is to increase myocardial contractility. It sensitizes and increases the binding efficiency of cardiac troponin in the myofibril to the calcium ions that are already present in systole. In normal hearts it increases the consumption of oxygen and energy to the same degree as dobutamine but ...