EFFECT OF ENDOGENOUS ADENOSINE ON ELECTRICALLY-EVOKED ACH SECRETION AT MAMMALIAN NEUROMUSCULAR JUNCTION (NMJ)

JAVIER GONZÁLEZ SANABRIA; ADRIANA LOSAVIO; MAXIMILIANO HURTADO PASO

Mar del Plata

Congreso; LXI REUNIÓN ANUAL DE LA SOCIEDAD ARGENTINA DE INVESTIGACIÓN CLÍNICA (SAIC); 2016

SAIC - SAI - SAFE

At mammalian NMJ, ATP is co-released with ACh, and metabolized via ecto-nucleotidases to adenosine (AD), which modulates ACh release through presynaptic inhibitory A1 or facilitatory A2A receptors (R), according to the amounts of extracellular AD. Our aim was to analyze the effect of endogenous AD on electrically-evoked ACh secretion when the nerve was stimulated at 0.5 Hz (50 pulses), 5 Hz (750 pulses) or 50 Hz (750 pulses or 5 bursts of 150 pulses, 20-s interburst interval). In phrenic diaphragm preparations (CF1 mice), we studied the action of the specific antagonist or agonist for A1R (DPCPX 0.1 μM, CCPA 500 nM) and for A2AR (SCH-58261 [SCH] 50 nM or PSB-0777 [PSB] 20 nM) upon EPPs amplitude. At 0.5 Hz (n=7) and 5 Hz (n=6), DPCPX did not change 1º EPP amplitude, mean EPPs amplitude, 20 last EPPs amplitude and 20 last EPPs/1º EPP ratio, while CCPA (0.5 Hz, n=4; 5 Hz n=5) significantly reduced 1º EPP amplitude, mean EPPs amplitude and 20 last EPPs. At 0.5 Hz, CCPA did not alter 20 last EPPs/1º EPP ratio but at 5 Hz this relation was higher than in control (p