I. Vonkugelgen et al., PRESYNAPTIC MODULATION OF THE RELEASE OF THE COTRANSMITTERS NORADRENALINE AND ATB, Fundamental and clinical pharmacology, 8(3), 1994, pp. 207-213
The release of both sympathetic co-transmitters, noradrenaline and ATP
, is modulated via presynaptic receptors. However, the degree of the m
odulation may differ indicating that the ratio of the released co-tran
smitters changes upon presynaptic receptor activation. For example, al
pha(2)-autoinhibition affects the release of noradrenaline more marked
ly than the release of ATP. Some sympathetic axon terminals possess pr
esynaptic P-2-purinoceptors which are activated by endogenous ATP. The
se receptors are a novel kind of autoreceptor: they mediate a presynap
tic negative feedback mechanism in which released ATP inhibits subsequ
ent co-transmitter release.