Evoked release from guinea pig cerebral cortex slices of endogenous 14C-labelled amino acids, labelled via D-[U-14C]glucose

1976 ◽  
Vol 54 (6) ◽  
pp. 949-952 ◽  
Author(s):  
S. J. Potashner
Keyword(s):  
Amino Acids ◽  
Cerebral Cortex ◽  
Guinea Pig ◽  
Electrical Field Stimulation ◽  
Mammalian Brain ◽  
Field Stimulation ◽  
Electrical Field ◽  
Endogenous Amino Acids ◽  
Cortex Slices

Release of endogenous amino acids labelled via D-[U-14C]glucose was compared with that of several exogenous labelled amino acids using slices of guinea pig cerebral cortex. Electrical field stimulation evoked a selective release of endogenous [14C]glutamate, [14C]aspartate, and γ-amino[14C]butyrate (14C-labelled GABA). The selectivity of release correlated well with 14C incorporation into endogenous amino acids. Calculations of the fraction of the tissue radio-activity released indicated that the selectivity was not an artifact due to differential incorporation. Because glucose in mammalian brain is metabolized almost entirely by the so-called 'large compartment', it is tentatively concluded that the releasable 'transmitter pool' of glutamate, aspartate, and GABA is located in this 'large compartment'.

Ca2+-dependence of the evoked release from guinea pig cerebral cortex slices of endogenous 14C-labelled amino acids, labelled via D-[U-14C]glucose

1976 ◽  
Vol 54 (6) ◽  
pp. 953-956 ◽  
Author(s):  
S. J. Potashner
Keyword(s):  
Amino Acids ◽  
Cerebral Cortex ◽  
Amino Acid ◽  
Guinea Pig ◽  
The Other ◽  
Major Portion ◽  
Free Medium ◽  
Spontaneous Release ◽  
Endogenous Amino Acids ◽  
Cortex Slices

Spontaneous and electrically evoked release of exogenous labelled amino acids and endogenous amino acids labelled from D-[U-14C]glucose were compared in control and Ca2+-free medium using guinea pig cerebral cortex slices. Spontaneous release of all labelled amino acids, except that of endogenous 14C-labelled threonine–serine–glutamine (unseparated) and exogenous [14C]aspartate, was doubled in Ca2+-free medium. The major portion of the electrically evoked release of endogenous [14C]glutamate, [14C]aspartate, γ-amino[14C]butyrate (14C-labelled GABA) and exogenous 3H-labelled GABA was Ca2+-dependent. More than half of the evoked release of the other labelled amino acids was Ca2+-independent. As the pattern of Ca2+-dependence of the evoked releases concurred with the selectivity of the evoked release for endogenous [14C]-glutamate, [14C]aspartate, and 14C-labelled GABA, it was concluded that these labelled amino acids were probably released from the amino acid 'transmitter pool'.

Effects of mucosal removal on guinea-pig airway smooth muscle responsiveness

1986 ◽  
Vol 70 (6) ◽  
pp. 571-575 ◽  
Author(s):  
Christopher Murlas
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Airway Smooth Muscle ◽  
Contractile Response ◽  
Electrical Field Stimulation ◽  
Physiological Salt Solution ◽  
Induced Responses ◽  
Field Stimulation ◽  
Electrical Field ◽  
Airway Mucosa

1. The contractile response to histamine, acetylcholine (ACh), KCl or electrical field stimulation (EFS) was examined in paired tracheal rings (one of each being denuded by mucosal rubbing), which were mounted in muscle chambers filled with a continuously aerated physiological salt solution at 37°C. 2. Removal of the respiratory mucosa increased the sensitivity of airway muscle to ACh, histamine and EFS, but not to KCl. The hypersensitivity of denuded rings to histamine and EFS was greater than to ACh. Atropine reduced the histamine hypersensitivity observed. 3. Pretreating intact preparations with indomethacin augmented their responsiveness to EFS, histamine and ACh. 4. Indomethacin augmentation of histamine- and EFS-induced responses was greater in preparations without epithelium. 5. We conclude that the airway mucosa may be associated with a factor that reduces airway smooth muscle responsiveness to stimulation.

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