title: Modulation of intracellular Ca2+ release and capacitative Ca2+ entry by CaMKII inhibitors in bovine vascular endothelial cells.
abstract: The effects of inhibitors of CaMKII on intracellular Ca2+ signaling were examined in single calf pulmonary artery endothelial (CPAE) cells using indo-1 microfluorometry to measure cytoplasmic Ca2+ concentration ([Ca2+]i). The three CaMKII inhibitors, KN-93, KN-62, and autocamtide-2-related inhibitory peptide (AIP), all reduced the plateau phase of the [Ca2+]i transient evoked by stimulation with extracellular ATP. Exposure to KN-93 or AIP alone in the presence of 2 mM extracellular Ca2+ resulted in a dose-dependent increase of [Ca2+]i consisting of a rapid and transient Ca2+ spike followed by a small sustained plateau phase of elevated [Ca2+]i. Exposure to KN-93 in the absence of extracellular Ca2+ caused a transient rise of [Ca2+]i, suggesting that exposure to CaMKII inhibitors directly triggered release of Ca2+ from intracellular endoplasmic reticulum (ER) Ca2+ stores. Repetitive stimulation with KN-93 and ATP, respectively, revealed that both components released Ca2+ largely from the same store. Pretreatment of CPAE cells with the membrane-permeable inositol 1,4,5-trisphosphate (IP3) receptor blocker 2-aminoethoxydiphenyl borate caused a significant inhibition of the KN-93-induced Ca2+ response, suggesting that exposure to KN-93 affects Ca2+ release from an IP3-sensitive store. Depletion of Ca2+ stores by exposure to ATP or to the ER Ca2+ pump inhibitor thapsigargin triggered robust capacitative Ca2+ entry (CCE) signals in CPAE cells that could be blocked effectively with KN-93. The data suggest that in CPAE cells, CaMKII modulates Ca2+ handling at different levels. The use of CaMKII inhibitors revealed that in CPAE cells, the most profound effects of CaMKII are inhibition of release of Ca2+ from intracellular stores and activation of CCE.
authors.affiliation: Dept. of Physiology, Loyola Univ. Chicago, 2160 South First Ave., Maywood, IL 60153, USA.
authors.forename: Ademuyiwa A S
authors.initials: AA
authors.lastname: Aromolaran
authors.forename: Lothar A
authors.initials: LA
authors.lastname: Blatter
mesh_terms: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000031:analogs & derivatives / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001596:Benzylamines / Q000494:pharmacology; D001693:Biological Transport, Active; D001896:Boron Compounds / Q000494:pharmacology; D002118:Calcium / Q000502:physiology*; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002417:Cattle; D002460:Cell Line; D042783:Endothelial Cells / Q000187:drug effects / Q000502:physiology*; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D004789:Enzyme Activation; D010455:Peptides / Q000494:pharmacology; D013449:Sulfonamides / Q000494:pharmacology; D000096926:Benzenesulfonamides
chemical_list: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000255:Adenosine Triphosphate; D001596:Benzylamines; D001896:Boron Compounds; D002118:Calcium; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D010455:Peptides; D013449:Sulfonamides; C503464:CaMKII inhibitor AIP; C072105:KN 93; D000096926:Benzenesulfonamides; C063302:KN 62; C109986:2-aminoethoxydiphenyl borate