Guanine nucleotide regulation of muscarinic receptor-mediated inositol phosphate formation in permeabilized 1321N1 cells
Carbachol and guanine nucleotides stimulate formation of the (/sup 3/H)inositol phosphates IP, IP2, and IP3 in saponin-permeabilized monolayers labelled with (/sup 3/H) inositol. Carbachol alone has little effect on formation of the (/sup 3/H) inositol phosphates (IPs), but GTP..gamma..S causes synergistic accumulation of (/sup 3/H)IPs to levels similar to those seen in intact cells. GTP, GppNHp, and GTP..gamma..S all support formation of the (/sup 3/H)IPs, with or without hormone, but GTP..gamma..S is the most effective. In the presence of GTP..gamma..S, the effect of carbachol is dose-dependent. Half-maximal and maximal accumulation of the (/sup 3/H)IPs occur at approx. 5 ..mu..M and approx. 100 ..mu..M carbachol, respectively; values close to those seen in intact cells. GTP..gamma..S alone stimulates formation of the (/sup 3/H)IPs after a brief lag time. The combination of GTP..gamma..S and carbachol both increases the rate of, and decreases the lag in, formation of the (/sup 3/H)IPs. LiCl increases (/sup 3/H)IP and IP2, but not IP3, accumulation; while 2,3-diphosphoglycerate substantially increases that of (/sup 3/H)IP3. GTP..gamma..S and carbachol cause formation of (/sup 3/H)IPs in the absence of Ca/sup + +/, but formation induced by GTP..gamma..S with or without carbachol is Ca/sup + +/-sensitive over a range of physiological concentrations. Although carbachol, Ca/sup + +/, and GTP..gamma..S all have effects on formation of (/sup 3/H)IPs, GTP..gamma..S appears to be a primary and obligatory regulator of phosphoinositide hydrolysis in the permeabilized 1321N1 astrocytoma cell.
- Research Organization:
- Univ. of California, San Diego
- OSTI ID:
- 6859438
- Report Number(s):
- CONF-8604222-; TRN: 87-010342
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:4; Conference: 70. annual meeting of the Federation of American Society for Experimental Biology, St. Louis, MO, USA, 13 Apr 1986
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CHOLINE
RECEPTORS
NUCLEOTIDES
BIOCHEMICAL REACTION KINETICS
PHOSPHOLIPIDS
HYDROLYSIS
ASTROCYTOMAS
DOSE-RESPONSE RELATIONSHIPS
GUANINE
TRACER TECHNIQUES
TRITIUM COMPOUNDS
TUMOR CELLS
ALCOHOLS
AMINES
AMMONIUM COMPOUNDS
ANIMAL CELLS
AROMATICS
AZAARENES
CHEMICAL REACTIONS
DECOMPOSITION
DISEASES
DRUGS
ESTERS
GLIOMAS
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
LIPIDS
LIPOTROPIC FACTORS
LYSIS
MEMBRANE PROTEINS
NEOPLASMS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PROTEINS
PURINES
QUATERNARY COMPOUNDS
REACTION KINETICS
SOLVOLYSIS
550201* - Biochemistry- Tracer Techniques