rhodanine and Tachycardia

Multiple-site optical recording of transmembrane voltage activity (MSORTV), using a voltage-sensitive dye and a 12 x 12-element photodiode array, was employed to monitor action potentials in the rat atrium. Atrial preparations including the sinus node area, caval area, and atrial septum were dissected from adult rat hearts and stained with a voltage-sensitive merocyanine-rhodanine dye (NK2761). For suppression of optical artefacts due to contractile movements, a bathing medium containing 2,3-butanedione monoxime (BDM: 10-20 mM) was used. The spread of spontaneous excitation from the pacemaker was assessed optically by timing the initiation of the action potential-related extrinsic absorption changes. The optical signals were recorded from more than 300 contiguous loci in the atrium by sliding the photodiode array over the image of the preparation; in this way, the intra-atrial conduction pattern of spontaneous excitation was mapped. The obtained maps revealed a non-radial spread of excitatory waves originating in the pacemaking area over the atrium. Furthermore, we also mapped the conduction pattern of long-lasting tachycardia-like excitation evoked by a short train of electrical stimulation (5-10 Hz, 1-2s) applied with a bipolar electrode. These maps suggest that excitatory waves are propagated in a circular pathway which often surrounds the ostium of the superior or inferior vena cava. Various patterns for the pathway were also demonstrated optically.

Topics: Action Potentials; Animals; Atrial Function; Cholinesterase Reactivators; Coloring Agents; Diacetyl; Electric Stimulation; Electrophysiology; Female; Heart Conduction System; Image Processing, Computer-Assisted; In Vitro Techniques; Male; Myocardial Contraction; Organ Preservation Solutions; Rats; Rats, Wistar; Rhodanine; Tachycardia; Thiazolidines

Circus-movement tachycardia was studied using voltage-sensitive merocyanine-rhodanine dyes (dye XVII and NK2761). Excitatory waves were optically measured simultaneously from eight different regions of a ring of tissue formed from frog atrium. Application of acetylcholine in Ca2+-free solution (10(-10)-10(-9) g/ml) shortened the duration of optical action signals to cause nonuniform change in optical signal durations in about 60% of the preparations. Circus-movement tachycardia was produced by proper reduction and regional nonuniformity of optical signal durations. Under these circumstances it is easy to evoke circus-movement tachycardia by giving an extra stimulus to the site that shows a difference in optical signal durations.

Topics: Acetylcholine; Action Potentials; Animals; Benzoxazoles; Fluorescent Dyes; Heart; Heart Atria; Microelectrodes; Rana catesbeiana; Rhodanine; Tachycardia; Thiazoles; Thiazolidines