The effect of carbachol, an acetylcholine receptor agonist, on rate of phosphatidylinositol (PI) turnover in cultured human meningioma cells was investigated. Exposure of meningioma cells for 2 h to carbachol (3.12-200 mumol/L) resulted in a dose-dependent stimulation of PI turnover to a maximum of 5.5-fold over basal controls. A time course study showed stimulation of IP3 formation after 30 s followed by increases in IP1 and IP2. The stimulatory effect of carbachol on PI turnover was completely abolished by the muscarinic receptor antagonist, atropine, but was unaltered by the nicotinic antagonist, hexamethonium. Reverse-transcription of meningioma-derived RNA into cDNA followed by amplification by the polymerase chain reaction using specific primers revealed presence of ml type muscarinic receptor mRNA. These results provide evidence that human meningioma cells possess muscarinic acetylcholine receptors the activation of which leads to PI hydrolysis.