[The cholinergic non-excitability phenomenon in the atrial myocardium of lower vertebrates].
Changes of electric activity induced by acetylcholine were studied in atrial myocardium of fishes (cod and carp) and reptilians (lizard and grass-snake). Standart microelectrode technique and novel method of optical mapping were used in the study. Acetylcholine (1-50 microM) provoked decrease of the action potential amplitude down to full inhibition of electrical activity in wide regions of atrium of cod and carp. We define this phenomenon as cholinergic inexcitability. In other regions excitation persisted even during action of 500 microM acetylcholine. In atria of lizard and grass-snake acetylcholine caused shortening of action potential without changes in it's amplitude. Local cholinergic inexcitability, shown in the atrial myocardium of fishes, is quite similar to the phenomenon, that was described earlier in the atria of frogs. It presents the heart of fish as an interesting model for study of mechanisms of cholinergic atrial arrhythmias initiation.
Abramochkin
D V
DV
Kuz'min
V S
VS
Sukhova
G S
GS
Rozenshtraukh
L V
LV
D000109:Acetylcholine / Q000494:pharmacology*; D000200:Action Potentials / Q000187:drug effects*; D000818:Animals; D020517:Atrial Appendage / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D018678:Cholinergic Agents / Q000494:pharmacology*; D005399:Fishes / Q000502:physiology*; D008839:Microelectrodes; D009206:Myocardium / Q000378:metabolism; D012104:Reptiles / Q000502:physiology*
D018678:Cholinergic Agents; D000109:Acetylcholine