kn-62 and herbimycin

The neutralization of the polyanionic surface of the podocyte by perfusion of kidneys with polycations, such as protamine sulfate, leads to a retraction of podocyte foot processes and proteinuria. This study investigates the effects of protamine sulfate or anionic, neutral, or cationic dextrans on the cytosolic calcium activity ([Ca2+]i) in podocytes.. [Ca2+]i was measured in single cultured differentiated mouse podocytes with the fluorescence dye fura-2/AM.. Protamine sulfate caused a concentration-dependent and partially reversible increase of [Ca2+]i (EC50 approximately 1.5 micromol/liter). Pretreatment of the cells with heparin (100 U/liter) inhibited the protamine sulfate-mediated increase of [Ca2+]i. Like protamine sulfate, diethylaminoethyl dextran (DEAE-dextran) concentration dependently increased [Ca2+]i in podocytes (EC50 approximately 20 nmol/liter), whereas dextran sulfate or uncharged dextran (both 10 micromol/liter) did not influence [Ca2+]i. A reduction of the extracellular Ca2+ concentration (from 1 mmol/liter to 1 micomol/liter) partially inhibited the protamine sulfate and the DEAE-dextran-induced [Ca2+]i response. Flufenamate (100 micromol/liter) or Gd3+ (10 micromol/liter), which are known to inhibit nonselective ion channels, did not influence the [Ca2+]i increase induced by protamine sulfate. In the presence of thapsigargin (50 nmol/liter), an inhibitor of the endoplasmic reticulum Ca2+-ATPase, both protamine sulfate and DEAE-dextran increased [Ca2+]i.. The data indicate that polycations increase podocyte [Ca2+]i. The increase of [Ca2+]i may be an early event in the pathogenesis of protamine sulfate-mediated retraction of podocyte foot processes.

Topics: 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; 3T3 Cells; Animals; Benzoquinones; Calcium Signaling; Cells, Cultured; DEAE-Dextran; Heparin; Kidney Glomerulus; Lactams, Macrocyclic; Marine Toxins; Mice; Muramidase; Oxazoles; Protamines; Quinones; Rifabutin; Staurosporine; Thapsigargin

1-(5-Isoquinolinesulfonyl1)-2-methylpiperazine hydrochloride (H-7), an inhibitor of protein kinases, has been shown to inhibit the thymocyte apoptosis induced by various apoptogenic agents. In the present study, when mouse thymocytes were pretreated with H-7, washed, and cultured for an additional time, apoptosis was induced depending on the preincubation time and the dose of H-7. The protein kinase C activity in the H-7-pretreated and -washed cells was not altered, suggesting that an alteration of a certain PKC isoform is related to both the triggering and the progression of apoptosis.

Topics: 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; Animals; Apoptosis; Benzoquinones; Calcium-Calmodulin-Dependent Protein Kinase Type 2; Calcium-Calmodulin-Dependent Protein Kinases; Cells, Cultured; Cyclic AMP-Dependent Protein Kinases; Cycloheximide; Dactinomycin; Enzyme Inhibitors; Isoenzymes; Isoquinolines; Lactams, Macrocyclic; Male; Mice; Mice, Inbred BALB C; Nucleic Acid Synthesis Inhibitors; Phosphorylation; Protein Kinase C; Protein Processing, Post-Translational; Protein Synthesis Inhibitors; Quinones; Rifabutin; RNA; Sulfonamides; T-Lymphocytes; Thymus Gland