Effects of purine compounds on cholinergic nerves. Specificity of adenosine and related compounds on acetylcholine release in electrically stimulated guinea pig ileum

The Development of Tachyphylaxis to Electrical Stimulation in Guinea‐pig Ileal Longitudinal Muscles and the Possible Participation of Adenosine and Adenine Nucleotides

“…Our previous experiments with guinea-pig ileum demonstrated that the inhibitory effect of adenosine on cholinergic nerves was specifically antagonized by theophylline and potentiated by dipyridamole and hexobendine. Thus it was suggested that adenosine reduced ACh release from intramural cholinergic nerves possibly in a specific manner (or through a specific receptor site) different from that of tetrodotoxin, adrenaline, strychnine and morphine (Hayashi et al, 1978). (Hayashi et al, 1978).…”

“…Thus it was suggested that adenosine reduced ACh release from intramural cholinergic nerves possibly in a specific manner (or through a specific receptor site) different from that of tetrodotoxin, adrenaline, strychnine and morphine (Hayashi et al, 1978). (Hayashi et al, 1978). It has been proposed that theophylline prevents the appearance of tachyphylaxis by competing with adenosine, presumably at the receptor site and that dipyridamole accelerates it by blocking adenosine uptake into the tissues (Satchell et al, 1972;Hayashi et al, 1978).…”

“…Effects of theophylline and dipyridamole on tachyphylaxis Theophylline and dipyridamole have been known to antagonize and potentiate the inhibitory actions of adenosine and adenine nucleotides in the guinea-pig ileum and taenia coli (Satchell, Lynch, Bourke & Burnstock, 1972;Sawynok & Jhamandas, 1976;Okwuasaba, Hamilton & Cook, 1977;Hayashi et al, 1978). In an attempt to test the possibility that endogenous adenosine derivatives may participate in the appearance of tachyphylaxis to nerve mediated responses, we have examined how the development of tachyphylaxis is influenced by theophylline and dipyridamole.…”

The influence of extracellular Ca2+ concentration on the inhibitory effect of adenosine in guinea-pig ileal longitudinal muscles.

“…In the previous paper, in which the actions of purine compounds on the cholinergic nerves were investigated in guinea-pig ileum, we reported that only adenosine derivatives reduced the electrically induced acetylcholine (ACh) release from the nerves, the most potent being adenosine, and in addition that the effect was selectively antagonized by xanthine derivatives such as theophylline and enhanced by dipyridamole and hexobendine (1). Also, observed was a progressive decline of amplitude of the contractile response, namely a development of tachyphylaxis, when the ileal longitudinal muscle was electrically stimulated by 30 Hz for 10 sec at 1 min intervals.…”

“…The pD2 value for morphine was significantly increased in low Ca 2+ and decreased in high Call (pD2 for morphine: Control (1.8 mM Ca 2+), 7.24±0.1 2; 0.9 mM Ca2+, 7.72±0.09; 3.6 mM Ca2+ 6.50±0.1 9,). It has been reported that the effect of adenosine was competitively an tagonized by theophylline in normal Ca 21 medium while the effect of morphine was not (1). The effect of theophylline on adenosine and morphine induced inhibition in 0.9 mM Ca 21 medium was then examined.…”