BETA-ADRENERGIC RECEPTOR-MEDIATED CALCIUM MOBILIZATION IN THE HUMAN JURKAT T-CELL LINE

The regulation of Ca2+ mobilization by beta-adrenergic receptor in the human Jurkat T cell line was investigated. Jurkat cells had a single class of beta-adrenergic receptor binding sites. Isoproterenol (ISP) caused the increase in cytosolic free Ca2+ concentration ([Ca2+](i)) in a dose-dependent manner. In the absence of extracellular Ca2+, the pretreatment with OKT3, an anti-CD3 antibody, did not affect a transient increase in [Ca2+](i) induced by the subsequent addition of ISP, and vice versa. On the other hand, the pretreatment with thapsigargin abolished the response of [Ca2+](i) to the subsequent additions of ISP and OKT3. In permeabilized Jurkat cells, the addition of cAMP released Ca2+ from the intracellular Ca2+ pool. Neither nimodipine nor H8, a protein kinase A inhibitor, affected the increase in [Ca2+](i) induced by ISP. The results suggest that cAMP accumulated by the activation of beta-adrenergic receptor may directly release Ca2+ from the inositol trisphosphate-insensitive intracellular Ca2+ pool in Jurkat T cells.