Release from synaptosomes

Also in cultured neuroendocrine pinealocytes K+-induced release of Asp was both Ca +-dependent and sensitive to botulinum toxin (Yatsushiro et al., 1997). To rule out involvement of exchange mechanisms in the K -induced release of Asp the authors used dihydrokainate, which is a non-transported inhibitor (see above) of the excitatory amino acid carrier (GLTl) found in the pinealocytes (Yamada et al., 1997). This treatment did not affect the K+-induced release, but inhibited Na -dependent sequestration of Asp into the pinealocytes. In addition they showed that the pinealocytes, which contain both the L-form the D-form of Asp, released only L-Asp upon membrane depolarization. This makes it further 

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Grady, S., Marks, M.J., Wonnacott, S., Collins, A.C. Characterization of nicotinic receptor-mediated [3H]dopamine release from synaptosomes prepared from mouse striatum. J. Neurochem. 59 848,1992. 

Kulak JM, McIntosh JM, Yoshikami D, Olivera BM (2001) Nicotine-evoked transmitter release from synaptosomes functional association of specific presynaptic acetylcholine receptors and voltage-gated calcium channels. J Neurochem 77 1581-9 Kuner R, Grunewald KH, Eisenhardt G et al (1999) Role of heteromer formation in GABAb receptor function. Science 283 74-7... 

Grady SR, Murphy KL, Cao J, Marks MJ, McIntosh JM, Collins AC (2002) Characterization of nicotinic agonist-induced [(3)H]dopamine release from synaptosomes prepared from four mouse brain regions. J Pharmacol Exp Ther 301 651-60 Graham B, Redman S (1994) A simulation of action potentials in synaptic boutons during presynaptic inhibition. J Neurophysiol 71 538 49... 

McMahon HT, Foran P, Dolly JO et al. (1992) Tetanus toxin and botulinum toxins type A and B inhibit gitamate, gamma-aminobutyric acid, aspartate, and met-enkephalin release from synaptosomes. Clues to the focus of action. J. Biol. Chem. 267 21338-43. 

Since ChAc is relatively easily released from synaptosome membranes, it is necessary to keep in mind that only a minor portion of the enzyme can be bound to membranes. If there are microenvironmental changes in pH within the terminal (e.g., due to the hydrolysis of ACh) a larger proportion of the enzyme could be membrane bound. 

METABOLISM OF PHOSPHATIDIC ACID AND PHOSPHATIDYLINOSITOL IN RELATION TO TRANSMITTER RELEASE FROM SYNAPTOSOMES... 

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