Abstract
We have introduced multiple-site optical recording of transmembrane voltage activity, using a fast merocyanine-rhodanine voltage-sensitive dye (NK2761) and a multi-element (16 × 16) photodiode array, to monitor action potentials in the artificial circuits made of the isolated rat atrium. The atrial wall preparation including the right or left auricle was dissected from the adult rat heart and an artificial hole was made in the center of the preparation. The preparation was then stained with a voltage-sensitive dye. For suppression of optical artefacts due to contractile movements, a bathing medium containing 2,3-butanedione monoxime (BDM: 20 mM) was used. The spread of spontaneous excitation was assessed optically by timing the initiation of the action potential-related extrinsic absorption changes. The electrical stimulation applied by a bipolar electrode evoked the sustained circus movement of the excitatory wave around the artificial hole. We have optically mapped the spatiotemporal patterns of the circus movement of excitation. These maps suggest that the circus movement observed in the artificial circuit resembles the basic mechanism of the tachycardia-like excitation observed in the intact isolated right atrial preparation, that we reported previously. On the bases of these maps, we considered the circus movement in the artificial circuit as the in vitro model of atrial flutter. [J Physiol Sci. 2007;57 Suppl:S211]
