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Abstract

Oyster Electrophysiology :Electrocardiogram Signal Recognition and Interpretation

Author(s): Frederico M.Batista, Deborah M.Power,and Adrian P. Harrison

After 100yearsofpublishedrecordingtracespertainingtotheoysterelectrocardiogram(ECG),werevisitedtheoriginal experimentsofEiger(1913),usingstate-of-the-artelectrophysiologyrecorders.OuraimwastoconfirmthatarecordableECG, similar to that of higher vertebrates, is present in the oyster heart. Portuguese oysters Crassostrea angulata, collected from the Guadianaestuary,Portugal,wereused.Theoystersweredrilledthroughtherightvalvetorevealthepericardium.Goldandsilver electrodes were placed through the hole and electrophysiological recordings were obtained. Stimulation of the oyster heart was performed in vivo and in vitro using a constant current power supply. Placement of electrodes around the heart revealed a trace that very closely matched the published ECG of Eiger (1913). However, we were unable to confirm that the recording was an ECG of the oyster heart. Moreover, measurements on isolated oyster hearts revealed a low conductivity (0.10 S m−1). We did, however, record a depolarization signal from what we believe to be the visceral ganglia, and this preceded contractions of the oysterheart.Ourfindingsindicatethatso-calledECGs,previouslyrecordedby[2]inOstreaedulis,butalsothe“ECG”recorded by[4]inC.virginicafromoysterhearts,areinfactanartifactarisingfromrelativemovementoftherecordingelectrodes,giving risetoabaselineshiftthatmimicsinsomewaysthePandQRSfeaturesofatypicalECG.Nevertheless,suchrecordingsprovide informationpertainingtoheartrateandarenotwithoutimportance.

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