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Both positive and negative inotropes are used in the management of various cardiovascular conditions. The choice of agent depends largely on specific pharmacological effects of individual agents with respect to the condition. One of the most important factors affecting inotropic state is the level of calcium in the cytoplasm of the muscle cell ...
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
Medications used include: diuretic agents, vasodilator agents, positive inotropes, ACE inhibitors, beta blockers, and aldosterone antagonists (e.g., spironolactone). Some medications which increase heart function, such as the positive inotrope milrinone, lead to increased death, and are contraindicated. [9] [10]
A positive dromotrope increases AV nodal conduction, and a negative dromotrope decreases AV nodal conduction. A lusitrope is an agent that affects diastolic relaxation. Many positive inotropes affect preload and afterload .
The positive inotropic effect of amrinone is mediated by the selective enhancement of high-gain CICR, which contributes to the contraction of myocytes by phosphorylation through cAMP dependent protein kinase A (PKA) and Ca 2+ calmodulin kinase pathways.
The stimulant inotropes, such as Digoxin, cause higher concentrations of calcium ions which increase contractility. Excess calcium (hypercalcemia) is also a positive inotrope. Drugs that are negative inotropes include beta blockers and calcium channel blockers. Hypoxia, acidosis, hyperkalemia are also negative inotropic agents. [citation needed]
Drugs that positively render the effects of catecholamines such as norepinephrine and epinephrine that enhance contractility are considered to have a positive inotropic effect. The ancient herbal remedy digitalis appears to have both inotropic and chronotropic properties that have been recorded encyclopedically for centuries and it remains ...
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 ...