cGMP is not required for capacitative Ca2+ entry in Jurkat T-lymphocytes.
In this study, we have addressed the potential role of cGMP in regulating calcium entry in Jurkat T-lymphocytes. These cells display capacitative Ca(2+)-entry in response to the intracellular Ca(2+)-ATPase inhibitor, thapsigargin (TG). In the presence of extracellular Ca2+, TG stimulates a sustained elevation of intracellular cGMP levels. In the absence of extracellular Ca2+, TG induces no apparent increase in the levels of cGMP. However, experiments using Mn2+, as a surrogate for Ca2+, demonstrated that TG increased the rate of divalent cation entry in the absence of extracellular Ca2+. Treatment of Jurkat cells with the guanylyl cyclase inhibitor, LY83583 (20 microM), completely blocked cGMP formation in response to TG. However, LY83583 treated cells still exhibited a sustained, albeit partially reduced, Ca2+ response induced by TG. These data demonstrate that, in Jurkat cells, the sustained formation of cGMP is dependent on elevated intracellular Ca2+, and that elevated levels of cGMP are not necessary for the activation of capacitative Ca2+ entry.
Bian
X
X
Laboratory of Cellular and Molecular Pharmacology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA.
Bird
G S
GS
Putney
J W
JW
D000634:Aminoquinolines / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D006152:Cyclic GMP / Q000494:pharmacology*; D005456:Fluorescent Dyes / Q000737:chemistry; D006801:Humans; D013601:T-Lymphocytes / Q000378:metabolism*
D000634:Aminoquinolines; D005456:Fluorescent Dyes; C041715:6-anilino-5,8-quinolinedione; D006152:Cyclic GMP; D002118:Calcium