Positive Inotropic Agents
Positive Inotropic Agents - Related Videos
01:26
Heart Failure Drugs: Inotropic Agents
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2024
Positive inotropic agents are commonly used as the first line of treatment for heart failure. One such agent is digoxin, derived from the genus Digitalis, which has been known for centuries but effectively utilized since 1785. However, these cardiac glycosides can have potentially toxic effects due to their mechanism of action, which involves inhibiting Na+/K+-ATPase and increasing contractility. Digoxin is absorbed orally and distributed in various tissues, including the CNS. It has a long...
09:54
A Recovery Cardiopulmonary Bypass Model Without Transfusion or Inotropic Agents in Rats
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Cited by 2 •
2018
Here, we present a protocol to describe a simple recovery cardiopulmonary bypass model without transfusion or inotropic agents in a rat. This model allows the study of the long-term multiple organ sequelae of cardiopulmonary bypass.
11:27
Preparation and In Vitro Characterization of Dendrimer-based Contrast Agents for Magnetic Resonance Imaging
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Cited by 5 •
2016
This protocol describes the preparation and characterization of a dendrimeric magnetic resonance imaging (MRI) contrast agent that carries cyclen-based macrocyclic chelates coordinating paramagnetic gadolinium ions. In a series of MRI experiments in vitro, this agent produced an amplified MRI signal when compared to the commercially available monomeric analogue.
10:19
Reducing Agents
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2023
Source: Vy M. Dong and Daniel Kim, Department of Chemistry, University of California, Irvine, CA Controlling the reactivity and selectivity during the synthesis of a molecule is very important criteria for chemists. This has led to the development of many reagents that allow chemists to pick and choose reagents suitable for a given task. Quite often, a balance between reactivity and selectivity needs to be achieved. This experiment will use IR spectroscopy to monitor the reaction and to...
07:40
Introducing Experimental Agents into the Mouse
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2023
Many investigations performed in mice (Mus musculus) require the administration of an experimental agent to the animal. For example, it may be of interest to test the efficacy of a specific therapy, to induce a pathologic condition, or to administer anesthesia or palliative care. In order to ensure safe and efficient delivery, it is important to consider a variety of factors prior to the administration of the treatment. This video, which reviews agent administration in the mouse, begins by...
FAQs
β1-adrenergic stimulation increases intracellular calcium availability in cardiomyocytes. The additional calcium supports stronger actin-myosin interaction, which intensifies cardiac muscle contraction and can increase stroke volume. This mechanism explains why agents such as dobutamine are pharmacologically distinct from drugs that enhance contractility through phosphodiesterase-3 inhibition or altered sodium-calcium exchange.
Phosphodiesterase-3 inhibition is one route to increasing intracellular calcium availability and strengthening myocardial contraction. Milrinone represents this mechanism within the positive inotropic agent class. Because its pathway differs from β1-adrenergic stimulation, comparing these mechanisms helps pharmacologists understand why individual agents can have different onset characteristics and clinical uses.
Digoxin is associated with altered sodium-calcium exchange, whereas dobutamine acts through β1-adrenergic stimulation and milrinone through phosphodiesterase-3 inhibition. These pathways converge on greater calcium availability inside cardiomyocytes, but their mechanistic differences help explain why the agents are not interchangeable and may differ in onset, application, and pharmacological behavior.
Stronger cardiac contraction can improve cardiac output, but positive inotropic therapy may also increase myocardial oxygen demand and create a risk of arrhythmias. This tradeoff makes the therapeutic response inseparable from safety assessment. Pharmacologists therefore view improved pump performance as a benefit that requires carefully controlled dosing and appropriate monitoring.
These agents are relevant when acute pump failure or circulatory shock requires improved cardiac output. By increasing contraction strength and potentially stroke volume, they can help stabilize selected patients with impaired cardiac performance. Their use is not uniform across all heart failure situations, because the specific drug, mechanism, onset, and clinical application differ.
Careful dosing and monitoring are central because the desired increase in cardiac output must be weighed against increased oxygen demand and arrhythmia risk. Pharmacological assessment should also account for the agent's mechanism, onset, and intended clinical use. These considerations support safer selection and adjustment when treating acute pump failure or circulatory shock.