Sodium Na+ channel Lab Report Example | Topics and Well Written Essays - 1250 words

Sodium Na+ Channel - Lab Report Example Patients with cardiac insufficiency receive drugs that affect the sodium pump in order to stabilize the heartbeat. Voltage-gated sodium channels. The family consists of at least 9 members and is largely responsible for action potential creation and propagation. The pore-forming alpha subunits are very large(up to 4,000 amino acids) and consist of four homologous repeat domains, comprising six transmembrane segments and transverse the cell membrane 24 times. They coassemble with a beta subunit that spans the membrane. Scorpion toxin has been used for classification of these channels. Diagram of a voltage-sensitive sodium channel ÃŽ ±-subunit. G - glycosylation, P - phosphorylation, S - ion selectivity, I - inactivation, positive (+) charges in S4 are important for transmembrane voltage sensing Frank H. Yu and William A. Catterall (2003) "Overview of the voltage-gated sodium channel family" in Genome Biol. 4(3): 207. ([http://www.pubmedcentral.gov/articlerender.fcgi?tool=pmcentrez&artid=153452 Full text online]). Class Ia agents depress phase 0 depolarization and reduce Vmax which prolongs the action potential duration by slowing conductance, these agents include quinidine, procainamide, and disopyramide and should be used in conjunction with an AV node blocking agent such as digoxin or a beta-blocker. Class Ib agents have the fast onset and offset kinetics and little or no effect at slower heartbeats. These include lidocaine, mexiletine, tocainide, and phenytoin. Class Ic agents markedly depress the phase 0 depolarization. They are indicated for life-threatening ventricular tachycardia or ventricular fibrillation and for the treatment of atrial fibrillation. They are potentially pro-arrhythmic, especially in settings of structural heart disease, as in post-myocardial infarction and contraindicated in such instances.  

Ukraines Transition from Socialism to Capitalism Essay

Ukraines Transition from Socialism to Capitalism - Essay Example Following the revolt, the rulers of Ukraine turned to Russia for protection and hence laid down the path towards Russian imperialism. This colonialism made a new distinction among the workforce in Ukraine. A large-scale labor migration from Russia occurred which acquired high skill and better pay job opportunities while the domestic workers suffered from a low wage and bad working conditions. The protests against such unjust and exploitative attitude lead to the upheaval of the 1917-1920 and 1942-1947 revolution. The struggle weakened because of the withdrawal of the Bolshevik members of Ukraine. In October 1917, the revolutions of Russia and Ukraine fused but the leaders in the parliament, Rada, who were against the notion of a Russian workers’ republic, decelerated the progress towards a Ukrainian socialist uprising. The Rada had diverged so much from the objectives of the Ukrainian mass that during its disposition in 1918 (by the Red Army) it had already lost its ground of support. In this so-called defense of sovereignty, the incident that took place was that these Rada leaders gave Ukraine away to German, Austrian, and Polish occupations. The year 1920 saw another upsurge to dispose of Russian colonialism by the Ukrainian Communist protesters. However, with the strengthening of the powers of Stalin and Russia, the dynamics of centralism shattered the rest of the hopes of national equality. In the 1930’s, a mixture of rapid industrialization and enforced collectivization sowed the seeds of a mass aggression. Millions of people died in the false famine of 1932-33 and a considerable number were deported to Siberia. Those who thought to venerate, analyze, or dissent these tragic incidents were either imprisoned or tortured.