PMID- 2440317
OWN - NLM
STAT- MEDLINE
DCOM- 19870818
LR  - 20171213
IS  - 0002-9513 (Print)
IS  - 0002-9513 (Linking)
VI  - 253
IP  - 1 Pt 2
DP  - 1987 Jul
TI  - Rectification of muscarinic K+ current by magnesium ion in guinea pig atrial 
      cells.
PG  - H210-4
AB  - Rectifying properties of the acetylcholine (ACh)-sensitive K+ channels were 
      studied using a patch-clamp method in single atrial cells prepared enzymatically 
      from adult guinea pig hearts. In the presence of micromolar concentration of 
      nonhydrolyzable guanosine 5'-triphosphate (GTP) analogue 
      5'-guanylylimidodiphosphate (GppNHp) and the absence of Mg2+ at the inner surface 
      of patch membrane [( Mg2+]i), the channel activity recovered in inside-out patch 
      condition. The single channel conductance became ohmic between -80 and +80 mV 
      (symmetrical 150 mM K+ solutions). The rapid relaxation of outward single channel 
      currents was disclosed on a depolarization. [Mg2+]i blocked the outward current 
      through the channel dose- and voltage-dependently and also induced a 
      dose-dependent increase in the channel activation. The apparent paradoxical role 
      of [Mg2+]i is important for the cholinergic control in the heart; 
      voltage-dependent Mg block ensures a low K+ conductance of cell membrane at the 
      plateau of action potentials during the exposure to ACh, thereby slowing the 
      heart rate without unfavorable shortening of the action potentials.
FAU - Horie, M
AU  - Horie M
FAU - Irisawa, H
AU  - Irisawa H
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - Am J Physiol
JT  - The American journal of physiology
JID - 0370511
RN  - 0 (Ion Channels)
RN  - 0 (Ions)
RN  - I38ZP9992A (Magnesium)
RN  - N9YNS0M02X (Acetylcholine)
RN  - RWP5GA015D (Potassium)
SB  - IM
MH  - Acetylcholine/*pharmacology
MH  - Animals
MH  - Electric Conductivity
MH  - Guinea Pigs
MH  - Heart Atria
MH  - Ion Channels/*physiology
MH  - Ions
MH  - Magnesium/*pharmacology
MH  - Myocardium/cytology/*metabolism
MH  - Potassium/*metabolism/physiology
EDAT- 1987/07/01 00:00
MHDA- 1987/07/01 00:01
CRDT- 1987/07/01 00:00
PHST- 1987/07/01 00:00 [pubmed]
PHST- 1987/07/01 00:01 [medline]
PHST- 1987/07/01 00:00 [entrez]
AID - 10.1152/ajpheart.1987.253.1.H210 [doi]
PST - ppublish
SO  - Am J Physiol. 1987 Jul;253(1 Pt 2):H210-4. doi: 10.1152/ajpheart.1987.253.1.H210.