PMID- 2436062
OWN - NLM
STAT- MEDLINE
DCOM- 19870515
LR  - 20190725
IS  - 0028-1298 (Print)
IS  - 0028-1298 (Linking)
VI  - 335
IP  - 2
DP  - 1987 Feb
TI  - Quinidine inhibition of the muscarine receptor-activated K+ channel current in 
      atrial cells of guinea pig.
PG  - 216-8
AB  - Postsynaptic mechanisms underlying the anticholinergic effects of quinidine were 
      examined in single atrial cells, using the tight-seal whole-cell recording 
      technique. The solution in the glass pipettes contained guanosine-5'-triphosphate 
      (GTP) or guanosine-5'-O-(3-thiotriphosphate) (GTP-gamma S, a non-hydrolyzable GTP 
      analogue). In both cases, acetylcholine (ACh), applied to the bath, induced a 
      specific K+ current. In GTP-loaded cells, quinidine in the bath solution 
      depressed the ACh-induced K+ current concentration-dependently. Atropine also 
      blocked the K+ current. On the other hand, in GTP-gamma S-loaded cells, the 
      ACh-induced current was not blocked by atropine and persisted even when ACh was 
      washed out from the bath, indicating that GTP-gamma S causes uncoupling of the K+ 
      channels from the muscarine receptors. Quinidine, however, did depress the 
      increased K+ current concentration-dependently. The percent inhibition curves for 
      quinidine to depress the K+ current were very similar between GTP-loaded and 
      GTP-gamma S-loaded cells. From these observations, we suggest that direct 
      inhibition of the muscarine receptor-activated K+ channel current by quinidine, 
      and not blockade of the muscarine receptor itself, is mainly responsible for the 
      anticholinergic effects of the drug in atrial myocytes.
FAU - Kurachi, Y
AU  - Kurachi Y
FAU - Nakajima, T
AU  - Nakajima T
FAU - Sugimoto, T
AU  - Sugimoto T
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - Germany
TA  - Naunyn Schmiedebergs Arch Pharmacol
JT  - Naunyn-Schmiedeberg's archives of pharmacology
JID - 0326264
RN  - 0 (Ion Channels)
RN  - 0 (Receptors, Muscarinic)
RN  - 0 (Thionucleotides)
RN  - 37589-80-3 (Guanosine 5'-O-(3-Thiotriphosphate))
RN  - 7C0697DR9I (Atropine)
RN  - 86-01-1 (Guanosine Triphosphate)
RN  - ITX08688JL (Quinidine)
RN  - N9YNS0M02X (Acetylcholine)
SB  - IM
MH  - Acetylcholine/pharmacology
MH  - Animals
MH  - Atropine/pharmacology
MH  - Guanosine 5'-O-(3-Thiotriphosphate)
MH  - Guanosine Triphosphate/analogs & derivatives/pharmacology
MH  - Guinea Pigs
MH  - Heart/drug effects
MH  - In Vitro Techniques
MH  - Ion Channels/*drug effects
MH  - Myocardium/*metabolism
MH  - Quinidine/*pharmacology
MH  - Receptors, Muscarinic/*drug effects
MH  - Thionucleotides/pharmacology
EDAT- 1987/02/01 00:00
MHDA- 1987/02/01 00:01
CRDT- 1987/02/01 00:00
PHST- 1987/02/01 00:00 [pubmed]
PHST- 1987/02/01 00:01 [medline]
PHST- 1987/02/01 00:00 [entrez]
AID - 10.1007/BF00177726 [doi]
PST - ppublish
SO  - Naunyn Schmiedebergs Arch Pharmacol. 1987 Feb;335(2):216-8. doi: 
      10.1007/BF00177726.