Chapter 14 P2-receptors controlling neurotransmitter release from postganglionic sympathetic neurones

Abstract

This chapter discusses the properties and the functional roles of P2-receptors present on postganglionic sympathetic neurons. A physiological role is well established for release inhibiting P2-receptors located at the axon terminals of postganglionic sympathetic neurons. These presynaptic P2-receptors are activated by cotransmitter ATP and operate as a kind of autoreceptor mediating a feedback inhibition of ongoing action potential evoked sympathetic transmitter release. In addition to release-modulating P2-receptors, postganglionic sympathetic neurons possess P2-receptors, activation of which causes the generation of action potentials and subsequently transmitter release. Excitatory P2-receptors located at the nerve cell bodies or dendrites of postganglionic sympathetic neurons have been proposed to be involved in fast synaptic neuro-neural transmission in sympathetic ganglia. Sympathetic neurons cultured from rat paravertebral ganglia possess two different subtypes of excitatory P2-receptors. Activation of both receptors induced the generation of action potentials and transmitter release. One receptor is an adenine nucleotide sensitive P2X-receptor. The other receptor is activated by uracil nucleotides and belongs most likely to the group of G-protein-coupled P2Y-receptors.