Adrenocorticotropic hormone stimulates a transient calcium uptake in rat lymphocytes.
Freshly isolated rat lymphocytes were tested for corticotropin (ACTH)-dependent calcium uptake. Physiological levels of corticotropin (0.01-1 nM) were found to stimulate both an uptake of 45Ca2+ and a rise in cAMP. The calcium uptake was delayed by 2 min after ACTH addition, but was rapid and transient after the onset of uptake. The extent of calcium uptake was dose dependent on the corticotropin concentration and reached a maximum by 1 nM. Several fragments of corticotropin were tested for activity; both full-length 1-39 and a functional truncated form, 1-25, had equivalent effects on 45Ca influx at 1 nM; however, alpha MSH-(1-13), ACTH-(11-24), or a mixture of alpha MSH and ACTH-(11-24) had no effect on 45Ca influx. Extracellular calcium uptake was blocked by the calcium channel blockers lanthanum, diltiazem, nifedipine, and omega-conotoxin. Splenic lymphocytes that express ACTH receptors had ligand-dependent calcium uptake, but thymocytes that lack ACTH receptors had no ligand-dependent calcium uptake. A mouse adrenal cell line, Y-1, showed the same 45Ca uptake kinetics. These findings demonstrate that both lymphocytes and adrenal cells have a functional ACTH-dependent calcium uptake mechanism.
Department of Physiology and Biophysics, University of Alabama, Birmingham 35294-0005.
B L
BL
Clarke
D R
DR
Moore
J E
JE
Blalock
D000311:Adrenal Glands / Q000737:chemistry / Q000166:cytology / Q000378:metabolism; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology*; D000818:Animals; D001483:Base Sequence; D002118:Calcium / Q000493:pharmacokinetics*; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000032:analysis / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D007811:Lanthanum / Q000494:pharmacology; D008214:Lymphocytes / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D008297:Male; D008969:Molecular Sequence Data; D009543:Nifedipine / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013950:Thymus Gland / Q000737:chemistry / Q000166:cytology / Q000378:metabolism; D013997:Time Factors; D020960:omega-Conotoxins
D010455:Peptides; D020960:omega-Conotoxins; C053423:Conus magus toxin; D007811:Lanthanum; D000324:Adrenocorticotropic Hormone; D000242:Cyclic AMP; D009543:Nifedipine; D002118:Calcium