IDENTIFICATION OF M3, M4 AND M5 SUBTYPES OF MUSCARINIC RECEPTOR MESSENGER-RNA IN HUMAN BLOOD MONONUCLEAR-CELLS

In this study we made use of the Reverse transcription-polymerase chai n reaction to analyze the expression of mRNA for the five subtypes of muscarinic acetylcholine receptors in human blood mononuclear cells. m RNA for m3, m4 and m5 subtypes was detected, while mRNA for mi and m2 muscarinic receptors was not found. Similar results were obtained for three different healthy human subjects studied. Interestingly, the m5 subtype was expressed at higher levels in blood mononuclear cells than in cerebral cortex. To our knowledge this is the first time that m5 m uscarinic receptor mRNA has been found outside of the central nervous system.