What is a monophasic action potential recorded by the Franz contact electrode?

by gest on M ay 3, 2016 D ow nladed fom After over 20 years of successful use of the Franz contact electrode technique by many others and myself (over 1000 publications to date), the recent paper by Kondo et al. [1] claims that it is not the tip electrode, but rather the distant-from-tip or bindifferentQ electrode that records the monophasic action potential (MAP). The introduction starts out by staging a contradiction between the classical MAP theory and the one stated by Franz [2] when in fact there is none really stated. The wording is confusing throughout their text and, in my view, of little help to foster the understanding of the complex issue of MAP genesis and recording. More important, the study by Kondo et al. [1] contains a plethora of methodological flaws of which only some can be addressed here. The isolated canine wedge preparation used by the authors is small compared to the BARD catheter used in this study. Despite the authors’ assertion, the BARD catheter is not bFranz-likeQ. It also is not drawn to proper scale in their figures. In reality, the BARD electrode shaft would look more like a btowerQ sitting on the small isolated wedge preparation. The Franz catheter was designed for human and large animal hearts and in those has provided high-resolution recordings of spatial heterogeneities in myocardial repolarisation. For smaller hearts or preparations we have developed greatly miniaturized MAP electrodes [3]. The study by Kondo et al. reports on a multitude of interventions (KCl application, local cooling, ATX-II application, multiple micro-electrode impalements which