title: Ca2+ uptake and energy supply of sheep heart mitochondria in presence of some calcium antagonists.
abstract: The action of the calcium antagonists nifedipine, bepridil, diltiazem and of an alpha adrenergic antagonist, prazosin, was studied on Ca2+ uptake and energy supply (i.e. oxidative phosphorylation) of sheep heart mitochondria. In order to appreciate an inhibition, uncoupler like, of the Ca2+ influx, a comparative study was made with DNP. The Ca2+ uptake was inhibited, at the concentrations tested, (less than or equal to 10(-3) M), only by bepridil, nifedipine and DNP: a 2.5.10(-4) M concentration of these drugs brought an inhibition of 95%, 65% and 100% respectively. The inhibition was accompanied by a decrease of the ADP:O ratio and the RCI except with nifedipine. It is suggested that bepridil could act more as an inhibitor-uncoupler and nifedipine as an inhibitor of the Ca2+ uptake uniporter; both leading to a decrease of the mitochondrial participation in the regulation of the cellular homeostasis. This phenomenon could contribute to the known clinical properties of bepridil and nifedipine.
mesh_terms: D000818:Animals; D015764:Bepridil; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D004110:Diltiazem / Q000494:pharmacology; D004734:Energy Metabolism / Q000187:drug effects*; D008929:Mitochondria, Heart / Q000187:drug effects / Q000378:metabolism*; D009543:Nifedipine / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D011759:Pyrrolidines / Q000494:pharmacology; D012756:Sheep
chemical_list: D002121:Calcium Channel Blockers; D011759:Pyrrolidines; D015764:Bepridil; D004110:Diltiazem; D009543:Nifedipine; D002118:Calcium; D011224:Prazosin