PMID- 16249676
OWN - NLM
STAT- MEDLINE
DCOM- 20060125
LR  - 20191210
IS  - 0003-3022 (Print)
IS  - 0003-3022 (Linking)
VI  - 103
IP  - 5
DP  - 2005 Nov
TI  - Effect of halothane on galphai-3 and its coupling to the M2 muscarinic receptor.
PG  - 1015-25
AB  - BACKGROUND: Halothane is an effective bronchodilator and inhibits airway smooth 
      muscle contraction in part by inhibiting intracellular signaling pathways 
      activated by the M2 muscarinic receptor and its cognate inhibitory heterotrimeric 
      guanosine-5'-triphosphate (GTP)-binding protein (G protein), Gi. This study 
      hypothesized that halothane inhibits nucleotide exchange at the alpha isoform-3 
      subunit of Gi (Galphai-3), but only when regulated by the M2 muscarinic receptor. 
      METHODS: GTP hydrolysis by Galphai-3 and the Galphai-3beta1gamma2HF heterotrimer 
      expressed in Spodoptera frugiperda cells was measured using a phosphohydrolase 
      assay with [gammaPi]-labeled GTP. Anesthetic binding to Galphai-3 was measured by 
      saturation transfer difference nuclear magnetic resonance spectroscopy. Galphai-3 
      nucleotide exchange was measured in crude membranes prepared from COS-7 cells 
      transiently coexpressing the M2 muscarinic receptor and Galphai-3. A radioactive 
      analog of GTP, [S]GTPgammaS, was used as a reporter for Galphai-3 nucleotide 
      exchange. RESULTS: Although spectroscopy demonstrated halothane binding to 
      Galphai-3, this binding had no effect on [gammaPi]-labeled GTP hydrolysis by the 
      Galphai-3beta1gamma2HF heterotrimer expressed in Spodoptera frugiperda cells, nor 
      basal Galphai-3 nucleotide exchange measured in crude membranes when the 
      muscarinic receptor agonist acetylcholine was omitted from the assay. Conversely, 
      halothane caused a concentration-dependent inhibition of Galphai-3 nucleotide 
      exchange with acetylcholine included in the assay. CONCLUSION: These data 
      indicate that despite halothane binding to Galphai-3, halothane has no direct 
      inhibitory effect on the intrinsic activity of the Galphai-3beta1gamma2HF 
      heterotrimer but inhibits M2 muscarinic receptor regulation of the heterotrimer. 
      This novel effect is consistent with the ability of halothane to inhibit airway 
      smooth muscle contraction and bronchoconstriction induced by acetylcholine.
FAU - Jin, Fang
AU  - Jin F
AD  - Department of Anesthesiology, Mayo Foundation, Rochester, Minnesota 55905, USA.
FAU - Wang, Shuyan
AU  - Wang S
FAU - Spencer, Joshua D
AU  - Spencer JD
FAU - Penheiter, Sumedha G
AU  - Penheiter SG
FAU - Streiff, John H
AU  - Streiff JH
FAU - Penheiter, Alan R
AU  - Penheiter AR
FAU - Warner, David O
AU  - Warner DO
FAU - Jones, Keith A
AU  - Jones KA
LA  - eng
GR  - HL-45532/HL/NHLBI NIH HHS/United States
GR  - HL-54757/HL/NHLBI NIH HHS/United States
PT  - Journal Article
PT  - Research Support, N.I.H., Extramural
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - Anesthesiology
JT  - Anesthesiology
JID - 1300217
RN  - 0 (Anesthetics, Inhalation)
RN  - 0 (Guanine Nucleotides)
RN  - 0 (Receptor, Muscarinic M2)
RN  - 0 (Recombinant Proteins)
RN  - 86-01-1 (Guanosine Triphosphate)
RN  - EC 3.6.5.1 (GNAI3 protein, human)
RN  - EC 3.6.5.1 (GTP-Binding Protein alpha Subunits, Gi-Go)
RN  - N9YNS0M02X (Acetylcholine)
RN  - UQT9G45D1P (Halothane)
SB  - IM
MH  - Acetylcholine/pharmacology
MH  - Anesthetics, Inhalation/*pharmacology
MH  - Animals
MH  - Baculoviridae/metabolism
MH  - COS Cells
MH  - Cell Membrane/drug effects/metabolism
MH  - Chlorocebus aethiops
MH  - Escherichia coli/drug effects/metabolism
MH  - GTP-Binding Protein alpha Subunits, Gi-Go/biosynthesis/drug effects/*metabolism
MH  - Guanine Nucleotides/metabolism
MH  - Guanosine Triphosphate/metabolism
MH  - Halothane/*pharmacology
MH  - Humans
MH  - Magnetic Resonance Spectroscopy
MH  - Receptor, Muscarinic M2/biosynthesis/*drug effects
MH  - Recombinant Proteins/metabolism
MH  - Transfection
EDAT- 2005/10/27 09:00
MHDA- 2006/01/26 09:00
CRDT- 2005/10/27 09:00
PHST- 2005/10/27 09:00 [pubmed]
PHST- 2006/01/26 09:00 [medline]
PHST- 2005/10/27 09:00 [entrez]
AID - 00000542-200511000-00016 [pii]
AID - 10.1097/00000542-200511000-00016 [doi]
PST - ppublish
SO  - Anesthesiology. 2005 Nov;103(5):1015-25. doi: 10.1097/00000542-200511000-00016.