Presence of different ATP receptors on rat midbrain single synaptic terminals. Involvement of the P2X(3) subunits.
Adenosine 5'-triphosphate (ATP) stimulates a [Ca(2+)](i) increase via specific ionotropic receptors, termed P2X receptors, in rat midbrain presynaptic terminals. A microfluorimetric technique enabled study of the [Ca(2+)](i) increase in isolated single synaptic terminals, showing that 33.4+/-2.5% of them responded to ATP. Immunological studies carried out, after functional studies, with specific anti-P2X receptor subunit antibodies showed only positive labelling with anti-P2X(3) antibodies in 23.5+/-1.7% of the terminals. All positively P2X(3) labelled synaptic terminals responded to ATP. Nevertheless, not all of them responded to alpha,beta-meATP, these representing 6.7+/-1.5% of the total. In addition, 9.8+/-2.3% of the terminals responded to ATP but exhibit negative P2X(3)-labelling. These results demonstrate the existence of a heterogeneous population of ionotropic ATP receptors at the presynaptic level.
Departamento de Bioquímica y Biología Molecular IV, Facultad de Veterinaria, Universidad Complutense de Madrid, 28040, Madrid, Spain.
M
M
Díaz-Hernández
R
R
Gómez-Villafuertes
F
F
Hernando
J
J
Pintor
M T
MT
Miras-Portugal
D000818:Animals; D003592:Cytophotometry; D007150:Immunohistochemistry; D008636:Mesencephalon / Q000737:chemistry* / Q000166:cytology; D017729:Presynaptic Terminals / Q000737:chemistry*; D051381:Rats; D018048:Receptors, Purinergic P2 / Q000032:analysis*; D058477:Receptors, Purinergic P2X3; D016708:Synaptophysin / Q000032:analysis; D013574:Synaptosomes / Q000737:chemistry
C546410:P2rx3 protein, rat; D018048:Receptors, Purinergic P2; D058477:Receptors, Purinergic P2X3; D016708:Synaptophysin