title: Interactions between several rare earth ions and calcium ion in vascular smooth muscle.
abstract: The effects of lutetium (Lu+++), europium (Eu+++) and neodymium (Nd+++) on 45Ca distribution, 45Ca movements and contractions were examined in rabbit aortic smooth muscle. Tension responses to norepinephrine were markedly inhibited by all three rare earth ions; K+-induced responses and those to histamine were partially blocked. Addition of 1.5 mM Lu+++, Eu+++ or Nd+++ to the bathing solution reduced 45Ca uptake (Nd+++ greater than Eu+++ greater than greater than Lu+++), produced a maintained increase in 45Ca efflux from strips of media-intimal layer washed out in a 0-Ca++ solution (Nd+++ greater than Eu+++ greater than Lu+++), and, when present during 45Ca incubation (before 45Ca washout), altered the release of 45Ca elicited by addition of 1.5 mM Ca++ during the 45Ca washout (inhibition by Nd+++ greater than Eu+++ greater than Lu+++). The 3-fold greater uptake of 45Ca in a 0-Ca++ and 1.5 mM Lu+++ solution than in an equivalent Sr++ solution results from a decreased effect of Lu+++ upon the slower 45Ca washout component. The actions of Lu+++ were quantitatively similar to those of low La+++ concentrations (0.05-0.10 mM), whereas those of Nd+++ and Eu+++ resembled effects obtained with equimolar concentrations of La+++. Thus, the three rare earth ions produce qualitatively similar alterations in 45Ca uptake and superficial binding. The difference observed can be attributed to variations in their affinity for superficial Ca++ binding sites and in their ability to block Ca++ uptake.
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects / Q000378:metabolism; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002132:Calcium Radioisotopes; D004347:Drug Interactions; D005063:Europium / Q000494:pharmacology; D005260:Female; D066298:In Vitro Techniques; D007811:Lanthanum / Q000494:pharmacology; D008187:Lutetium / Q000494:pharmacology; D008297:Male; D008674:Metals, Rare Earth / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism*; D009354:Neodymium / Q000494:pharmacology; D011817:Rabbits; D013324:Strontium / Q000494:pharmacology
chemical_list: D002132:Calcium Radioisotopes; D008674:Metals, Rare Earth; D009354:Neodymium; D005063:Europium; D008187:Lutetium; D007811:Lanthanum; D002118:Calcium; D013324:Strontium