Functional and molecular identification and characterization of cardiac M3 and M4 muscarinic acetylcholine receptors

Pilocarpine modulates the cellular electrical properties of mammalian hearts by activating a cardiac M3 receptor and a K+ current

“…Recently, the existence of M 3 receptors in canine atrial myocytes has been convincingly demonstrated with both functional and molecular evidence in our laboratory. We found that the cardiac M 3 receptors are functionally coupled to a novel type of delayed rectifier K + channels ( Shi et al ., 1998a , 1998b ) and we named this K + current I KM3 (M 3 receptor‐mediated K + current). We have confirmed that the cardiac M 3 receptors and I KM3 can be activated by tetramethylammonium ( Shi et al ., 1998b ) and choline ( Shi et al ., 1998c ).…”

“…We found that the cardiac M 3 receptors are functionally coupled to a novel type of delayed rectifier K + channels ( Shi et al ., 1998a , 1998b ) and we named this K + current I KM3 (M 3 receptor‐mediated K + current). We have confirmed that the cardiac M 3 receptors and I KM3 can be activated by tetramethylammonium ( Shi et al ., 1998b ) and choline ( Shi et al ., 1998c ). Preliminary data have been obtained in our laboratory indicating that pilocarpine can also activate a K + current with properties almost identical to TMA‐ or choline‐induced currents in dog atrial cells and the stimulation of mAChRs, likely the M 3 receptor subtype, is required for the current activation ( Wang et al ., 1998 ).…”