Ca2+-channel blocker

The risk of atrial flutter is a 2 1 transmission to the ventricles generating a high ventricular rate. The therapeutic goal is to reduce transmission to 3 1 or 4 1 by administration of either (3-adrenoceptor antagonists, Ca2+ channel blockers or amiodarone. Quinidine must not be used in this arrhythmia, since it accelerates AV-conduction due to its vagolytic effect. 

Class IV antiarrhythmic drugs are Ca2+ channel blockers, which predominantly slow sinus rate and atrioventricular conduction and thus are used in the treatment of supraventricular tachyarrhythmias. These drugs exert a pronounced negative inotropic effect. 

Ca2+ is an important intracellular second messenger that controls cellular functions including muscle contraction in smooth and cardiac muscle. Ca2+ channel blockers inhibit depolarization-induced Ca2+ entry into muscle cells in the cardiovascular system causing a decrease in blood pressure, decreased cardiac contractility, and antiarrhythmic effects. Therefore, these drugs are used clinically to treat hypertension, myocardial ischemia, and cardiac arrhythmias. 

Ca2+ Channel Blockers. Figure 1 Most voltage-gated Ca2+ channels exist as a hetero-oligomeric complex of several subunits, a 1 subunits form the Ca2+-selective ion pore and contain the voltage-sensors of the channel. 

All three classes also inhibit depolarization-induced contraction of venous smooth muscle in vitro. However, venous relaxation does not substantially contribute to the hemodynamic actions of Ca2+ channel blockers. 

Epidemiological and case-control studies suggested that Ca2+ channel blockers cause increased risk for... 

Dihydropyridine receptor (DHPR) is a member of voltage-dqiendent Ca2+ channels (CaVi, L-type), which specifically binds to dihydropyridine derivatives, a group of the Ca2+ channel blockers. Cav 1.1 works as the voltage sensor for skeletal muscle contraction, and Cay 1.2, as Ca2+-influx channel for cardiac muscle contraction. 

Voltage-dependent Ca2+ Channels Ca2+ Channel Blockers Ryanodine Receptor... 

Vascu la r/n on vascular disorders NS 1608, NS-4, NS1609 (also Ca2+ channel blocker)... 

A large number of diugs interfere with the smooth muscle contraction. These compounds lower blood pressure and are referred to as antihypertensive. In this section, only those coumpounds will be mentioned that have a direct effect on smooth muscle tone. Phenylephrine is an agonist on most smooth muscles and activates ax adrenoceptors. Carbachol is an agonist on some smooth muscles and activates contraction through muscarinic receptors. Blockers of the ax-adrenoceptors such as prazosin and urapidil are competitive inhibitors of the ax-receptor in vascular and bladder smooth muscle. Phenoxybenzamine is an ineversible blocker of ax receptors and phentol-amine blocks ax and a2 receptors. Ca2+ channel blockers such as the dihydropyiidines, phenylalkyla-mines and benzothiazepines lower smooth muscle tone by blocking the L-type calcium channel. 

Vasodilators are a group of dtugs, which relax the smooth muscle cells of the blood vessels and lead to an increased local tissue blood flow, a reduced arterial pressure and a reduced central venous pressure. Vasodilators reduce the cardiac pre-load as well as after-load and thereby reduce cardiac work. They are used in a variety of conditions including hypertension, cardiac failure and treatment/prevention of angina pectoris. Major groups are Ca2+-channel blockers (e.g. dihydropyridines), NO-donators (e.g. organic nitrates), K+-channel openers (minoxidil), phosphodiesterase inhibitors (e.g. sildenafil), Rho-kinase inhibitors (e.g. Y27632) or substances with unknown mechanism of action (e.g. hydralazine). Inhibitors of the... 

Butyrophenones Butyrylcholinesterase C2 Domain C Kinase C-reactive Protein Ca2+-ATPase Ca2+-binding Proteins Ca2+ Channel Ca2+ Channel Antagonists Ca2+ Channel Blockers... 

Nimodipine A voltage-operated Ca2+ channel blocker with potential benefits in treating cognitive deficits and managing opiate and alcohol detoxification. 

The blood pressure of a 65-year-old male is well controlled by a Ca2+" channel blocker that is used to treat his essential hypertension. When placed on cimetidine to control symptoms related to gastroesophageal reflux disease (GERD), he has episodes of dizziness. I low does cimetidine s effect on Ca2+ channel blockers account for the dizziness ... 

Ca2+ channel blocker, long-acting nitrate therapy... 

Nelson We have seen Ca2+ channel blockers block the voltage dependence of the frequency of the STOCs. 

Nelson We can induce waves, and add a Ca2+ channel blocker. The average Ca2+ goes down, the arteries relax and the waves continue on. 

Nelson Gil Wier, in your paper with Mordy Blaustein, you applied Ca2+ channel blockers, the arteries relaxed and the waves continued, didn t they ... 

In total, antagonizing direct upstream control over the nNOS isoform can be achieved in part by application of internal and external Ca2+ channel blockers, Ca2+ buffering agents, hyperpolarizing agents or selective nNOS inhibitors such as 6 or 7-nitroindazole, l-(2-trifluoromethylphenyl) imidazole or 6-phenyl-2-aminopyridines [131-133],... 

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