Halothane inhibits the cholinergic-receptor-mediated influx of calcium in primary culture of bovine adrenal medulla cells
Adrenal medulla cells are cholinoceptive cells. Stimulation of the acetylcholine receptor causes the influx of Ca to the cells, and Ca acts as the coupler of the stimulus-secretion coupling. In this study, the authors investigated the effects of halothane on the receptor-mediated influx of /sup 45/Ca using cultured bovine adrenal medulla cells. Halothane at clinical concentrations (0.5-2%) inhibited the influx of /sup 45/Ca caused by carbachol, with simultaneous inhibition of catecholamine secretion. The influx of /sup 45/Ca and the secretion of catecholamines caused by K depolarization were inhibited by a large concentration of Mg, which competes with Ca at Ca channels, but not inhibited by halothane. Inhibition of the /sup 45/Ca influx by halothane was not overcome by increase in the carbachol concentration. Inhibition of the /sup 45/Ca influx by halothane was examined in comparison with that caused by a large concentration of Mg by the application of Scatchard analysis as the function of the external Ca concentration. Halothane decreased the maximal influx of /sup 45/Ca without altering the apparent kinetic constant of Ca to Ca channels. On the contrary, a large concentration of Mg increased the apparent kinetic constant without altering the maximal influx of /sup 45/Ca. Based on these findings, the authors suggest that inhibition of the /sup 45/Ca influx by halothane was not due to the direct competitive inhibition of Ca channels, nor to the competitive antagonism of agonist-receptor interaction. As a possibility, halothane seems to inhibit the receptor-mediated activation of Ca channels through the interference of coupling between the receptor and Ca channels.
- Research Organization:
- Kyushu Univ. School of Medicine, Japan
- OSTI ID:
- 5682454
- Journal Information:
- Anesthesiology; (United States), Vol. 4
- Country of Publication:
- United States
- Language:
- English
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ACETYLCHOLINE
RECEPTORS
ANESTHETICS
BIOLOGICAL EFFECTS
CALCIUM
MEMBRANE TRANSPORT
ADRENAL GLANDS
ANIMAL CELLS
CALCIUM 45
CATECHOLAMINES
CATTLE
MAGNESIUM
POTASSIUM
TRACER TECHNIQUES
ALKALI METALS
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METALS
AMINES
AMMONIUM COMPOUNDS
ANIMALS
AROMATICS
AUTONOMIC NERVOUS SYSTEM AGENTS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BODY
CALCIUM ISOTOPES
CENTRAL NERVOUS SYSTEM DEPRESSANTS
DAYS LIVING RADIOISOTOPES
DOMESTIC ANIMALS
DRUGS
ELEMENTS
ENDOCRINE GLANDS
ESTERS
EVEN-ODD NUCLEI
GLANDS
HYDROXY COMPOUNDS
INTERMEDIATE MASS NUCLEI
ISOTOPE APPLICATIONS
ISOTOPES
MAMMALS
MEMBRANE PROTEINS
METALS
NEUROREGULATORS
NUCLEI
ORGANIC COMPOUNDS
ORGANS
PARASYMPATHOMIMETICS
PHENOLS
POLYPHENOLS
PROTEINS
QUATERNARY COMPOUNDS
RADIOISOTOPES
RUMINANTS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques