Abstract
Author(s): Frederico M.Batista, Deborah M.Power,and Adrian P. Harrison
After 100yearsofpublishedrecordingtracespertainingtotheoysterelectrocardiogram(ECG),werevisitedtheoriginal experimentsofEiger(1913),usingstate-of-the-artelectrophysiologyrecorders.Ouraimwastoconï¬rmthatarecordableECG, 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 conï¬rm 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.Ourï¬ndingsindicatethatso-calledECGs,previouslyrecordedby[2]inOstreaedulis,butalsothe“ECG”recorded by[4]inC.virginicafromoysterhearts,areinfactanartifactarisingfromrelativemovementoftherecordingelectrodes,giving risetoabaselineshiftthatmimicsinsomewaysthePandQRSfeaturesofatypicalECG.Nevertheless,suchrecordingsprovide informationpertainingtoheartrateandarenotwithoutimportance.
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