Nicotinic and muscarinic acetylcholine responses in differentiated PC12 cells.
Nicotinic and muscarinic acetylcholine (ACh) responses were investigated in PC12 cells using the conventional whole-cell and nystatin perforated patch techniques. With the nystatin perforated patch, ACh induced three kinds of ionic currents: a rapid transient inward current, a subsequent transient outward current and a long-lasting slow inward current, whereas only a transient inward current was recorded by conventional whole-cell patch. The transient rapid inward current was mimicked by nicotine, but not by muscarine. On the contrary, the transient outward current and the long-lasting slow inward current were mimicked by muscarine but not by nicotine. Both nicotinic and muscarinic antagonists inhibited the transient inward current and the subsequent outward current in a concentration-dependent manner. The current-voltage relationship for the nicotine-induced transient current showed an inward rectification and the reversal potential was close to the Na+ equilibrium potential. The ACh-, muscarine-, CCh- and oxotremorine-M induced outward currents increased in a sigmoidal fashion with an increase in the concentration. Neither McN-A-343, an M1 agonist, nor oxotremorine, an M2 agonist, mimicked the muscarinic response. The reversal potential of the muscarinic response was close to the K+ equilibrium potential. The muscarinic response was not affected by pre-treatment with pertussis toxin but was enhanced by pre-treatment with Li+. In the cells perfused with Ca(2+)-free external solution, only the first application of ACh induced the muscarinic response. Calmodulin antagonists reversibly blocked the muscarinic response in a concentration-dependent manner.(ABSTRACT TRUNCATED AT 250 WORDS)
Furukawa
K
K
Department of Neurophysiology, Tohoku University School of Medicine, Sendai, Japan.
Nabekura
J
J
Akaike
N
N
D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D002463:Cell Membrane Permeability; D004533:Egtazic Acid / Q000494:pharmacology; D018738:Hexamethonium; D006584:Hexamethonium Compounds / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects*; D009116:Muscarine / Q000494:pharmacology*; D009414:Nerve Growth Factors / Q000494:pharmacology; D009538:Nicotine / Q000494:pharmacology*; D009761:Nystatin; D016716:PC12 Cells; D010276:Parasympatholytics / Q000494:pharmacology; D010890:Pirenzepine / Q000031:analogs & derivatives / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000502:physiology*; D011978:Receptors, Nicotinic / Q000187:drug effects / Q000502:physiology*; D014403:Tubocurarine / Q000494:pharmacology
D006584:Hexamethonium Compounds; D009414:Nerve Growth Factors; D010276:Parasympatholytics; D011976:Receptors, Muscarinic; D011978:Receptors, Nicotinic; D009761:Nystatin; D018738:Hexamethonium; D010890:Pirenzepine; D004533:Egtazic Acid; D009538:Nicotine; D001285:Atropine; D009116:Muscarine; D002217:Carbachol; D000109:Acetylcholine; C048593:otenzepad; D011188:Potassium; D014403:Tubocurarine