Angiotensin II-stimulated cortisol secretion is mediated by phospholipase D

Angiotensin II (Ang-II) regulates a variety of cellular functions including cortisol secretion. In the present report, we demonstrate that Ang-II activates phospholipase D (PLD) in zona fasciculata (ZF) cells of bovine adrenal glands, and that this effect is associated to the stimulation of cortisol secretion by this hormone. PLD activation was dependent upon extracellular Ca 2+, and was blocked by inhibition of protein kinase C (PKC). Using the reverse transcription–polymerase chain reaction technique, we demonstrated that ZF cells express both PLD-1 and PLD-2 isozymes. Primary alcohols, which attenuate the formation of phosphatidate (the product of PLD), and cell-permeable ceramides, which inhibit PLD potently, blocked Ang-II-stimulated cortisol secretion. Furthermore, propranolol or chlorpromazine, which are potent inhibitors of phosphatidate phosphohydrolase (PAP) (the enzyme that produces diacylglycerol from phosphatidate), also blocked cortisol secretion. These data suggest that the PLD/PAP pathway plays an important role in the regulation of cortisol secretion by Ang-II in ZF cells.