title: Circus-movement tachycardia in frog atrium monitored by voltage-sensitive dyes.
abstract: Circus-movement tachycardia was studied using voltage-sensitive merocyanine-rhodanine dyes (dye XVII and NK2761). Excitatory waves were optically measured simultaneously from eight different regions of a ring of tissue formed from frog atrium. Application of acetylcholine in Ca2+-free solution (10(-10)-10(-9) g/ml) shortened the duration of optical action signals to cause nonuniform change in optical signal durations in about 60% of the preparations. Circus-movement tachycardia was produced by proper reduction and regional nonuniformity of optical signal durations. Under these circumstances it is easy to evoke circus-movement tachycardia by giving an extra stimulus to the site that shows a difference in optical signal durations.
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001583:Benzoxazoles / Q000378:metabolism*; D005456:Fluorescent Dyes / Q000378:metabolism*; D006321:Heart / Q000503:physiopathology*; D006325:Heart Atria / Q000503:physiopathology; D008839:Microelectrodes; D011892:Rana catesbeiana; D012236:Rhodanine / Q000031:analogs & derivatives / Q000378:metabolism*; D013610:Tachycardia / Q000503:physiopathology*; D013844:Thiazoles / Q000378:metabolism*; D053778:Thiazolidines
chemical_list: D001583:Benzoxazoles; D005456:Fluorescent Dyes; D013844:Thiazoles; D053778:Thiazolidines; C025279:merocyanine-rhodanine; D012236:Rhodanine; D000109:Acetylcholine