(±)-Verapamil-d3 (hydrochloride) (Item No. 18452) is intended for use as an internal standard for the quantification of verapamil (hydrochloride) (Item No. 14288) by GC- or LC-MS. Verapamil is the prototypical blocker of L-type calcium channels that produces excitation-contraction uncoupling in cardiac muscle by preventing the slow-inward current of calcium ions. Verapamil can also block calcium fluxes in vascular smooth muscle. It has both peripheral and coronary vasodilator effects (IC50 = 0.38 μM in guinea pig aortic strip) and has been used to control hypertension, angina, cardiac arrhythmia, and vascular headaches. Verapamil has also been used in cell biology as an inhibitor of drug efflux pump proteins such as P-glycoprotein, which are often over-expressed in certain tumor cell lines.
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