Caffeine effects on buccal muscles of Aplysia.
1. Caffeine (35-70 mM) elicited contractions of Aplysia buccal muscle El. In a Ca2+-free medium, in which ACh-elicited contractions rapidly fail, caffeine elicited contractions of approximately the same size as in normal medium. 2. 5-HT (10(-8) M and 10(-7) M) did not enhance caffeine-elicited contractions. 3. Lower concentrations (1-10 mM) of caffeine inhibited ACh-elicited contractions. Caffeine (7 mM) reduced the contraction by 80%. 4. Caffeine (7 mM) reduced ACh-elicited depolarization by 60%. 5. Caffeine (7 mM) increased 45Ca2+ influx into Aplysia buccal muscle I5. The stimulation of influx of 45Ca2+ by 10(-3) M ACh was non-additive with the stimulation caused by caffeine, and 7 mM caffeine reduced the influx caused by 10(-3) M ACh.
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001048:Aplysia / Q000378:metabolism*; D002110:Caffeine / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D002610:Cheek / Q000378:metabolism; D004594:Electrophysiology; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D012623:Seawater / Q000032:analysis; D012701:Serotonin / Q000494:pharmacology
D012701:Serotonin; D002110:Caffeine; D000109:Acetylcholine; D002118:Calcium