Ver�nderungen des Belichtungspotentials der Retina des Einsiedlerkrebses (Eupagurus bernhardus L.) bei Vergiftung des Stoffwechsels und bei Adaptation

Abstract

1. The action potential of the retina of the hermit crab Eupagurus bernhardus L. resulting from exposure to light has been measured with external electrodes. 2. Three measurements of the retinal action potentials (RAP's) were taken to observe the changes of the RAP's quantitatively: a) the amplitude of the maximum hmax, to characterize the height of the RAP's; b) the amplitude of the plateau he,measured at the end of the stimulus for taking the shape quotient hmax/he; c) the peak amplitude time tmax. 3. The changes of the RAP's under the influence of metabolic inhibitors (2,4-Dinitrophenol 0,2 mM/1; Potassiumcyanide 1,0 mM/1; Sodiumazide 1,0 mM/1) have been studied under constant stimulus conditions. 4. Under the influence of the metabolic inhibitors the RAP's soon become smaller and finally under these conditions the excitability of the retina is lost. 5. Some minutes after washing out the inhibitor RAP's again can be evoked, these increasing in size with time. 6. The three inhibitors manifest similar effects on the RAP's; however, they differ in reaction time. 7. The excitability of the retina, which has been lost by poisoning, was not restorable by use of positive and negative polarizing currents. 8. The changes of the RAP's in the course of dark adaptation under constant stimulus conditions and the changes by different intensities of the stimulating light are measured and compared with the alterations of the RAP's induced by metabolic inhibitors. 9. When the intensity of the light stimuli increases, the amplitude hmax of the RAP's and the shape quotient hmax/hegrow in size and the peak amplitude time tmax decreases. 10. In the first phase of the influence of the metabolic inhibitors the changes of the height of the RAP's are similar to those produced by decreasing intensities of the stimuli, whereas the changes of the shape measured by the shape quotient hmax/heand tmax are similar to those produced by increasing intensities of the light stimuli. In the second phase of the inhibitors' action, both, the changes of height and shape of the RAP's are similar to those produced by decreasing intensity of the stimuli. 11. The changes of the RAP's under the influence of the inhibitors are very similar to the changes of the RAP's in the course of dark adaptation, when compared in the reverse direction of time. They are also rather similar to the changes of the RAP's when the resting potential of the photoreceptor cells is decreased under the influence of increasing potassium concentration in the extracellular solution. 12. It is suggested that under the influence of metabolic inhibitors the resting potential of the photoreceptor cells will decrease and the concentration of rhodopsin probably also will decrease.