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Early afterdepolarizations can result in torsades de pointes, tachycardia, and other arrhythmias. [3] EADs can be triggered by hypokalemia and drugs that prolong the QT interval, including class Ia and III antiarrhythmic agents, as well as catecholamines. [1] Afterhyperpolarizations can also occur in cortical pyramidal neurons.
Cells with a defective G 2-M checkpoint will undergo apoptosis or death after cell division if they enter the M phase before repairing their DNA. [1] The defining biochemical feature of this checkpoint is the activation of M-phase cyclin-CDK complexes, which phosphorylate proteins that promote spindle assembly and bring the cell to metaphase. [2]
Though many studies have shown various cell types directing the differentiation of M cells, new research characterizes the molecular pathways that guide M cell differentiation. More recently, through loss-of-function and rescue-phenotype studies, RANKL is shown to be a receptor activator of NF-κB ligand and play a role in differentiation of M ...
Action potential in a neuron, showing depolarization, in which the cell's internal charge becomes less negative (more positive), and repolarization, where the internal charge returns to a more negative value. Most cells in higher organisms maintain an internal environment that is negatively charged relative to the cell's exterior.
In eukaryotes, the cell cycle consists of four main stages: G 1, during which a cell is metabolically active and continuously grows; S phase, during which DNA replication takes place; G 2, during which cell growth continues and the cell synthesizes various proteins in preparation for division; and the M phase, during which the duplicated ...
The cell cycle is a series of complex, ordered, sequential events that control how a single cell divides into two cells, and involves several different phases. The phases include the G1 and G2 phases, DNA replication or S phase, and the actual process of cell division, mitosis or M phase. [ 1 ]
Afterhyperpolarization, or AHP, is the hyperpolarizing phase of a neuron's action potential where the cell's membrane potential falls below the normal resting potential. This is also commonly referred to as an action potential's undershoot phase. AHPs have been segregated into "fast", "medium", and "slow" components that appear to have distinct ...
The increasing voltage in turn causes even more sodium channels to open, which pushes V m still further towards E Na. This positive feedback continues until the sodium channels are fully open and V m is close to E Na. [7] [8] [20] [21] The sharp rise in V m and sodium permeability correspond to the rising phase of the action potential. [7] [8 ...