Calcium entry blockers and the forearm arterial bed
The smooth muscle cells in the walls of blood vessels are endowed with several mechanisms by which the concentration of calcium in the cytosol can be raised and contraction initiated [1, 2]. One important system is that of the voltage-dependent calcium channels in the plasma membrane. Voltage-dependent channels, as their name implies, open to permit the influx of calcium when the membrane is depolarised either spontaneously or in response to a stimulus; some channels with similar characteristics are, however, thought to be linked to α2-adrenoceptors and may thus be directly activated by noradrenaline. The influx of calcium through channels of the voltage-dependent type is inhibited by calcium entry blockers such as verapamil, diltiazem and compounds of the dihydropyridine group including nifedipine and nitrendipine.
KeywordsSodium Nitroprusside Calcium Entry Resistance Vessel Forearm Blood Flow Primary Hypertension
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