title: The interaction of lanthanides with isolated sarcoplasmic reticulum vesicles from rabbit skeletal muscle.
abstract: The interaction of lanthanides with isolated sarcoplasmic reticulum (SR) vesicles from rabbit skeletal muscle and the effects of lanthanides on 45Ca2+ uptake by the vesicles were studied. 153Gd3+ was taken up by the vesicles in the absence of ATP and oxalate in a time-dependent manner, reaching a maximum total accumulation of 380 nmol 153Gd3+/mg protein after 20 min with 200 microM 153Gd3+. This 153Gd3+ accumulation was not washed out by 1 mM EGTA. The addition of ATP induced the release of 87% of the bound 153Gd3+, leaving behind irreversibly-accumulated 153Gd3+. Pre-incubation of the vesicles with lanthanides in the absence of ATP and oxalate inhibited 45Ca2+ uptake without affecting Ca2+-ATPase activity. The percent inhibition of 45Ca2+ uptake increased with length of pre-incubation of the vesicles with lanthanides, reaching 33% after 20 min of pre-incubation. Increasing the 45Ca2+ concentration or adding ATP or oxalate to the preincubation medium abolished these inhibitory effects on 45Ca2+ uptake.
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D005682:Gadolinium / Q000378:metabolism* / Q000494:pharmacology; D007700:Kinetics; D009132:Muscles / Q000378:metabolism*; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism*
chemical_list: D005682:Gadolinium; D002118:Calcium