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The adrenergic receptors or adrenoceptors are a class of G protein-coupled receptors that are targets of many catecholamines like norepinephrine (noradrenaline) and epinephrine (adrenaline) produced by the body, but also many medications like beta blockers, β2 agonists and α2 agonists, which are used to treat high blood pressure and asthma, for example.
A neurotransmitter receptor is a membrane receptor protein that is activated by a neurotransmitter. Chemicals on the outside of the cell, such as a neurotransmitter, can bump into the cell's membrane and along the membrane we can find receptors. If a neurotransmitter bumps into its corresponding receptor, they will bind and can trigger other events to occur inside the cell. Therefore, a membrane receptor is part of the molecular machinery that allows cells to communicate with one another. A neurotransmitter receptor is a class of receptors that specifically binds with neurotransmitters as opposed to other molecules.
A metabotropic receptor is a type of membrane receptor that initiates a number of metabolic steps to modulate cell activity. The nervous system utilizes two types of receptors: metabotropic and ionotropic receptors. While ionotropic receptors form an ion channel pore, metabotropic receptors are indirectly linked with ion channels through signal transduction mechanisms, such as G proteins.
In neuroscience, an excitatory postsynaptic potential (EPSP) is a postsynaptic potential that makes the postsynaptic neuron more likely to fire an action potential. This temporary depolarization of postsynaptic membrane potential, caused by the flow of positively charged ions into the postsynaptic cell, is a result of opening ligand-gated ion channels. These are the opposite of inhibitory postsynaptic potentials (IPSPs), which usually result from the flow of negative ions into the cell or positive ions out of the cell. EPSPs can also result from a decrease in outgoing positive charges, while IPSPs are sometimes caused by an increase in positive charge outflow. The flow of ions that causes an EPSP is an excitatory postsynaptic current (EPSC).
In biochemistry and pharmacology, receptors are chemical structures, composed of protein, that receive and transduce signals that may be integrated into biological systems. These signals are typically chemical messengers which bind to a receptor and cause some form of cellular/tissue response, e.g. a change in the electrical activity of a cell. There are three main ways the action of the receptor can be classified: relay of signal, amplification, or integration. Relaying sends the signal onward, amplification increases the effect of a single ligand, and integration allows the signal to be incorporated into another biochemical pathway. Receptors in the biological field were discovered in the 19th Century by German biologist Christina Bonass.
An inotrope is an agent 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.
Cardiogenic shock (CS) is a medical emergency resulting from inadequate blood flow due to the dysfunction of the ventricles of the heart. Signs of inadequate blood flow include low urine production, cool arms and legs, and altered level of consciousness. People may also have a severely low blood pressure and heart rate.
Ligand-gated ion channels (LICs, LGIC), also commonly referred to as ionotropic receptors, are a group of transmembrane ion-channel proteins which open to allow ions such as Na+, K+, Ca2+, and/or Cl− to pass through the membrane in response to the binding of a chemical messenger (i.e. a ligand), such as a neurotransmitter.
Molecular neuroscience is a branch of neuroscience that observes concepts in molecular biology applied to the nervous systems of animals. The scope of this subject covers topics such as molecular neuroanatomy, mechanisms of molecular signaling in the nervous system, the effects of genetics and epigenetics on neuronal development, and the molecular basis for neuroplasticity and neurodegenerative diseases. As with molecular biology, molecular neuroscience is a relatively new field that is considerably dynamic.
Dobutamine is a medication used in the treatment of cardiogenic shock and severe heart failure. It may also be used in certain types of cardiac stress tests. It is given by injection into a vein or intraosseous as a continuous infusion. The amount of medication needs to be adjusted to the desired effect. Onset of effects is generally seen within 2 minutes.
Myocardial contractility represents the innate ability of the heart muscle (cardiac muscle or myocardium) to contract. The ability to produce changes in force during contraction result from incremental degrees of binding between different types of tissue, that is, between filaments of myosin (thick) and actin (thin) tissue. The degree of binding depends upon the concentration of calcium ions in the cell. Within an in vivo intact heart, the action/response of the sympathetic nervous system is driven by precisely timed releases of a catecholamine, which is a process that determines the concentration of calcium ions in the cytosol of cardiac muscle cells. The factors causing an increase in contractility work by causing an increase in intracellular calcium ions (Ca++) during contraction.
The term dromotropic derives from the Greek word δρόμος drómos, meaning "running", a course, a race. A dromotropic agent is one which affects the conduction speed in the AV node, and subsequently the rate of electrical impulses in the heart.
A PDE3 inhibitor is a drug which inhibits the action of the phosphodiesterase enzyme PDE3. They are used for the therapy of acute heart failure and cardiogenic shock.
Bathmotropic often refers to modifying the degree of excitability specifically of the heart; in general, it refers to modification of the degree of excitability of musculature in general, including the heart. It especially is used to describe the effects of the cardiac nerves on cardiac excitability. Positive bathmotropic effects increase the response of muscle to stimulation, whereas negative bathmotropic effects decrease the response of muscle to stimulation. In a whole, it is the heart's reaction to catecholamines. Conditions that decrease bathmotropy cause the heart to be less responsive to catecholaminergic drugs. A substance that has a bathmotropic effect is known as a bathmotrope.
Beta adrenergic agonists or beta agonists are medications that relax muscles of the airways, causing widening of the airways and resulting in easier breathing. They are a class of sympathomimetic agents, each acting upon the beta adrenoceptors. In general, pure beta-adrenergic agonists have the opposite function of beta blockers: beta-adrenoreceptor agonist ligands mimic the actions of both epinephrine- and norepinephrine- signaling, in the heart and lungs, and in smooth muscle tissue; epinephrine expresses the higher affinity. The activation of β1, β2 and β3 activates the enzyme, adenylate cyclase. This, in turn, leads to the activation of the secondary messenger cyclic adenosine monophosphate (cAMP); cAMP then activates protein kinase A (PKA) which phosphorylates target proteins, ultimately inducing smooth muscle relaxation and contraction of the cardiac tissue.
Cellular neuroscience is a branch of neuroscience concerned with the study of neurons at a cellular level. This includes morphology and physiological properties of single neurons. Several techniques such as intracellular recording, patch-clamp, and voltage-clamp technique, pharmacology, confocal imaging, molecular biology, two photon laser scanning microscopy and Ca2+ imaging have been used to study activity at the cellular level. Cellular neuroscience examines the various types of neurons, the functions of different neurons, the influence of neurons upon each other, and how neurons work together.
Omecamtiv mecarbil (INN), previously referred to as CK-1827452, is a cardiac-specific myosin activator. It is being studied for a potential role in the treatment of left ventricular systolic heart failure.
Istaroxime is an investigational drug originally patented and developed by the Italian pharmaceutical company Sigma-Tau. Istaroxime is now under development for treatment of acute decompensated heart failure by CVie Therapeutics. CVie Theraputics is a Taiwanese pharmaceutical company owned by Lee's Pharmaceutical Holdings Limited, that in July 2012 has acquired from Sigma-Tau, the patents and rights on istaroxime, and related compounds. It is still in early-stage development, having been evaluated in phase two clinical trials. Istaroxime is an innovative medication as it is an effective treatment for both systolic and diastolic heart failure. Systolic heart failure is characterized by impaired ventricular emptying, caused by reduced contractility, and diastolic dysfunction is defined by defective ventricular filling, caused by the heart's inability to properly relax between beats. Intracellular calcium fluxes regulate both contraction and relaxation. Cardiac muscle cells from patients with heart failure show smaller amounts of peak calcium in their cytoplasm during contraction, and slower removal., The mishandling of intracellular calcium is often due to problems in the cells’ ability to mediate calcium influx, and sequestration of calcium back in the sarcoplasmic reticulum.,
A channel modulator, or ion channel modulator, is a type of drug which modulates ion channels. They include channel blockers and channel openers.
Ionotropic GABA receptors (iGABARs) are ligand-gated ion channel of the GABA receptors class which are activated by gamma-aminobutyric acid (GABA), and include:
References
- ↑ Neuroscience (Dale Purves), Third Edition, table 20:2