Possible Interaction: Adenosine and Barium

“ Adenosine (0.5-100 microM) reduced the magnocellular preoptic nucleus and substantia innominata cholinergic neuronal firing rate by activating an inwardly rectifying potassium current that reversed at -82 mV and was blocked by barium (100 microM).”

“ Adenosine also partially inhibited barium current in these neurons.”

“Alphaxalone and 5 alpha-pregnan-3 alpha-ol-20-one also at low concentrations potentiated the inhibitory effect of adenosine alone and in the presence of 1 mM barium which blocked adenosine activated potassium channels.”

“ Adenosine (100 microM) reduced the duration of control action potentials and action potentials prolonged by 1 mM barium.”

“In order to eliminate effects of these agents on potassium channels, experiments were performed in the presence of barium , 1 mM. This concentration increased potential size, and reduced the inhibitory effect of adenosine on population spike size, but not synaptic potential size.”

“The ED50 was approximately 10 μM. The effect of adenosine 5′‐diphosphate (ADP) or adenosine 5′‐monophosphate (AMP), in the presence of barium , on membrane potential was less than that of ATP.”

“ Adenosine (10−5M) reduces the contractile response of the guinea‐pig isolated ileum to 5‐hydroxytryptamine or barium more than the responses to acetylcholine or histamine.”

“These results suggest that adenosine effects a blockade of the indirect responses to barium or 5‐hydroxytryptamine mediated through intrinsic nerves and has a weak direct inhibitory effect on the smooth muscle cells of this tissue.”