(±)-Felodipine-d₅is intended for use as an internal standard for the quantification of (±)-felodipine by GC- or LC-MS. (±)-Felodipine is an inhibitor of L-type calcium channels.¹It induces relaxation of precontracted isolated porcine coronary artery segments (EC₅₀= 0.15 nM), which highly express L-type calcium channels.²(±)-Felodipine is selective for L-type calcium channels over N-, R-, and P/Q-type channels at 10 µM, as well as the T-type Ca_v3.2 channel (IC₅₀= 6.8 µM).^1,3(±)-Felodipine preferentially inhibits L-type calcium channels in isolated rat portal vein over rat left ventricle (IC₅₀s = 33.9 and 3,981 nM, respectively).⁴It decreases mean arterial blood pressure and total peripheral resistance in a rabbit model of hypertension induced by renal artery ligation when administered intravenously at doses of 30 and 100 nmol/kg.⁵

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