- Alomone Labs Isradipine blocks L-type Ca2+ currents in Xenopus oocytes.A. Time course of L-type channel (CaV1.2+α2δ1+β1a) activity before and during applications of 200 nM and 1 μM Isradipine (#I-100) (indicated by bars) and upon wash. Holding potential was -80 mV and currents were elicited every 10 seconds by 100 ms ramp to +40 mV. B. Superimposed example current traces (plotted against the corresponding ramp voltage) before and during application of 200 nM and 1 μM Isradipine as indicated (taken from the experiment described in A).
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L-type (CaV1), voltage-gated Ca2+ channels are plasma membrane protein complexes which allow the passage of Ca2+ ions into cells following depolarization of the membrane potential. L-type channels are widely expressed in cardiac and smooth muscle where they control contraction and therefore were recognized as a therapeutic target for cardiovascular diseases1,2.
Isradipine is a dihydropyridine that acts as a L-type, voltage-gated Ca2+ channel blocker and is used in the clinic to treat hypertension3,4. Isradipine inhibits L-type channels expressed in Xenopus oocytes with IC50 = 0.2 µM at a holding potential of -80 mV and the inhibition is state dependent and increases with reduced membrane hyperpolarization4. Slow excitatory synaptic currents in dopaminergic neurons in slices of rat substantia nigra pars compacta and ventral tegmental area, which were evoked by a train of focally delivered electrical stimuli, were depressed by isradipine (30 nM-100 µM) in a concentration-dependent and reversible manner5. In addition, isradipine, was shown recently to be a putative effective treatment for Parkinson’s disease, by affecting particularly the excitability of certain CaV1.3 expressing dopaminergic neurons6. In a pancreatic cell line, insulin secretion triggered by 16.7 mM glucose, was completely abolished by 5 µM isradipine7.
Isradipine (#I-100) is a highly pure, synthetic, and biologically active compound.