Calcium release from membrane-bound calcium pool induced by ACTH.
We examined the effect of ACTH on the binding of Ca2+ to the plasma membrane of rat fat cells. Synthetic I-24 ACTH reduced the binding of 45Ca to the fat cell membrane dose-dependently. Whereas verapamil significantly increased binding, Ca ionophore A23187 significantly reduced it. These results suggest that ACTH induced the promoted release of Ca2+ from the plasma membrane-bound Ca pool into cytosol. ACTH-induced binding of 45Ca to the fat cell membrane occurred at at least two binding sites, i.e., high and low affinity binding sites. Epinephrine did not significantly influence 45Ca binding, showing an evident difference in the Ca2+ dependence of the lipolytic actions of ACTH and epinephrine.
D000273:Adipose Tissue / Q000378:metabolism; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology*; D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002122:Calcium Chloride / Q000378:metabolism; D002132:Calcium Radioisotopes; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D004837:Epinephrine / Q000494:pharmacology; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013806:Theophylline / Q000494:pharmacology
D002132:Calcium Radioisotopes; D007328:Insulin; D003994:Bucladesine; D000324:Adrenocorticotropic Hormone; D013806:Theophylline; D002122:Calcium Chloride; D002118:Calcium; D004837:Epinephrine