title: Adenosine effects upon transmitter release parameters in the Mg2+-paralyzed neuro-muscular junction of frog.
abstract: The influence of adenosine upon the process of transmitter release was investigated in Mg2+-paralyzed frog neuromuscular junction by using conventional microelectrophysiological techniques and binomial statistical analysis. The statistical parameters used were: m (mean number of quanta released per impulse), p (the probability of quantal release) and n (store of quanta available for release). Adenosine decreased the mean quantal content (m) by reducing n. This effect appeared to be dependent upon the free intracellular Ca2+. The nucleoside competed with the transmitter releasing effects of ouabain and increased the amount of effective Ca2+ necessary for quantal release. It did not change the slope of release parameters modification during low-frequency facilitation. The data are discussed in terms of a physical model of release.
mesh_terms: D000241:Adenosine / Q000494:pharmacology*; D000818:Animals; D001001:Anura; D002118:Calcium / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology*; D009469:Neuromuscular Junction / Q000187:drug effects*; D018377:Neurotransmitter Agents / Q000378:metabolism*; D010042:Ouabain / Q000494:pharmacology; D011898:Ranidae; D013997:Time Factors
chemical_list: D018377:Neurotransmitter Agents; D010042:Ouabain; D008274:Magnesium; D000241:Adenosine; D002118:Calcium