Abstract
The action potential of the ventricle of the carp was measured by the optical method using laser light and WW781. WW781 is a voltage sensitive dye and fluorescence is changed by the membrane potential. The purposes of this study is to obtain basic data of the optical properties of WW781 and to measure the spike phase of the action potential of the ventricle for multi sites optical monitoring using a laser scanning system. In order to select light source, absorption spectra of WW781 in ethanol and in Ringer's solution were measured. As the absorption band was from 550nm to 635nm, He-Ne laser emitting at 632.8nm was selected. Fluorescence emission pumped by He-Ne laser was only detected from the dye in ethanol and wavelength of fluorescence maximum was 655nm. The ventricle was removed from the carp and was stained with a solution of WW781 (0.1mg/ml in Ringer's solution) for 30min. The staining period was determined by comparison of fluorescence emission spectra obtained from the ventricles which were stained for several periods. Only reflection of pumping light was observed from the ventricle stained for short period. It was necessary a staining period of 30min to get large fluorescence. After staining, absorption band of WW781 was from 590nm to 660nm. Time course of fluorescence emmision from the stained ventricle was recorded. In order to check light scattering arisen by contraction of the ventricle, we monitored time course of reflected light from the surface of the ventricle at the same time. Fluorescence emission intensity increased 2% during the spike phase. However the reflected light intensity did not change. Because the contraction occurred after the spike phase, both optical intensities changed similarly. He-Ne laser is a useful light source for optical measuring of membrane potential with WW781.
