Vasoactive substances induce cytoskeletal changes in cultured rat glomerular epithelial cells.

Abstract

Angiotensin II (ANG II), atrial natriuretic peptide III (ANP), and sodium nitroprusside (SNP) alter capillary hydraulic conductivity in isolated glomeruli. These agents also affect cyclic nucleotide levels of glomerular epithelial cells (GEC). ANG II increases cAMP, whereas ANP and SNP increase cGMP. The effects of these vasoactive substances on GEC cytoskeleton were tested by incubating cells from primary cultures or an established cell line with each agent. Changes in the cytoskeleton were assessed by staining for F-actin with Bodipy phallacidin and for tubulin with NBD-colcemid. Control cells exhibited short bundles of F-actin or stress fibers near the base of the cells. These were frequently arranged in parallel and occasionally appeared to radiate from the center of the cell. Microtubules were arranged in a fine network throughout the cell with increased density adjacent to the nucleus and within the nucleolus. Incubation of GEC with 10(-7) M ANG II, cholera toxin, or 8Br-cAMP for 2 at 37 degrees C resulted in rearrangement of F-actin into distinct stellate patterns with a decrease in the relative intensity of the peripheral staining, all concurrent with a fivefold increase in intracellular cAMP. The incubation of GEC with 10(-6) M ANP or 10(-7) M SNP for 2 h at 37 degrees C resulted in apparent disassembly of stress fibers, sparse and more diffuse fluorescence, and some increase of fluorescence at the periphery of the cells, all concurrent with a 10-fold increase in intracellular cGMP. Cytochalasin D incubation led to complete disassembly of actin filaments.(ABSTRACT TRUNCATED AT 250 WORDS)