nk-2367 and merocyanine-rhodanine

The wavelength dependence of optical action potentials was studied using voltage-sensitive merocyanine-rhodanine, merocyanine-oxazolone, and oxonol dyes in the isolated rat atrium preparation. Most of the dyes had action spectra that were similar to those reported in other preparations. Species-to-species difference was observed with a merocyanine-oxazolone dye.

Topics: Action Potentials; Animals; Atrial Function; Benzenesulfonates; Benzoxazoles; Electric Stimulation; Electrophysiology; Female; Fluorescent Dyes; Heart Atria; Male; Optics and Photonics; Oxazolone; Rats; Rats, Wistar; Rhodanine; Spectrometry, Fluorescence; Thiazolidines

The optically recorded action potentials of the frog atrial muscles which lack transverse tubules showed different features from those reported by Heiny and Vergara (Heiny JA, Vergara J. Optical signals from surface and T system membranes in skeletal muscle fibers. J Gen Physiol 1982;80:203-230) in skeletal muscles (Fujishiro N, Kawata H. The wavelength dependence of optically recorded action potentials in the atrial muscles of the bullfrog (Rana catesbeiana). Comp Biochem Physiol 1996;114A:153-157). We examined whether or not the differences were consistent in other atrial muscles which lack transverse tubules with guinea pig atrial muscles. Two dyes (merocyanine rhodanine and merocyanine oxazolone) were used, and the dependence of the maximum rising phase of the optical signals on the wavelength of the incident beam was analyzed. No dependence was observed between them, and this finding was consistent with the structure of the membrane system of the guinea pig atrial muscles. The optical signals recorded at 718 nm of the incident beam from the guinea pig atrial muscles which stained with merocyanine oxazolone showed a more prominent second rising phase after the initial rapid rising phase of the optical signal than that recorded in the frog atrial muscles. This phase was not observed in the optical signals recorded at other wavelengths. The features of the optically recorded action potentials in guinea pig atrial muscles were consistent with those recorded in frog atrial muscles. Nifedipine did not affect the second rising phase.

Topics: Action Potentials; Animals; Atrial Function; Benzoxazoles; Coloring Agents; Guinea Pigs; Heart; In Vitro Techniques; Optics and Photonics; Oxazolone; Rhodanine; Temperature; Thiazolidines

Changes in dye absorption and fluorescence produced by electrical stimulation were measured in frog optic nerves stained with voltage-sensitive dyes. Following a single maximal stimulus applied through a suction electrode, the change in transmitted light intensity consisted of two components: one representing an axonal compound action potential and the second a slow depolarizing afterpotential which appeared to arise from the glial cells. The following results support this interpretation: during a train of stimuli the depolarizing potentials sum and can exceed 80% of the initial spike amplitude while the spike amplitude itself remains essentially constant. Thus, the axons cannot have undergone significant depolarization during the train. Optical recordings with simultaneous microelectrode recordings from the glial cells indicate that the change in glial membrane potential during the train has a time-course similar to that of the slow optical response. We conclude that voltage-sensitive dyes can monitor potential changes in both neurons and glia.

Topics: Animals; Axons; Benzoxazoles; Electric Stimulation; Electrophysiology; Microelectrodes; Neuroglia; Optic Nerve; Oxazoles; Oxazolone; Rana pipiens; Rhodanine; Thiazoles; Thiazolidines