Elevations of intracellular cAMP result in a change in cell shape that resembles dome formation in cultured rat glomerular epithelial cells.

Cultured glomerular epithelial cells form a continuous monolayer of polyhedral-shaped cells. PGE2 (1 microgram/ml) in the presence of the phosphodiesterase inhibitor isobutylmethylxanthine (MIX) markedly raises intracellular and medium cyclic AMP (cAMP) levels at 20 min (intracellular: MIX alone, 112 +/- 6.6 pmol cAMP/mg protein, MIX plus PGE2, 2252 +/- 63 pmol cAMP/mg protein; medium: MIX, 20.6 +/- 2.1 pmol cAMP/mg protein; MIX plus PGE2, 117 +/- 3.8 pmol cAMP/mg protein). By 2 h, when cellular and medium cAMP levels were still elevated, the cells underwent a change in shape that was similar to dome formation (15 to 20% of the monolayer changing shape). Derivatives of cAMP [i.e. dibutyryl and 8-(4-chlorophenylthio)-cAMP], when added to the incubation medium also caused shape change in glomerular epithelial cells at 2 h; cAMP itself did not. The formation of domes has been used as a morphological indicator of the vectorial transport of salt and water in other cultured epithelial cells.