RESUMO
It was observed that the outer segments of the frog visual rods orient along the direction of an externally applied static electric field. The orientation ability of the rod outer segments seems to be fuelled by the cell energy. The dipolar moment per rod was determined using a model which considers rod outer segments as rigid dipoles interacting with the electric field in a viscous medium. The mean dipolar charge of ROS was determined as being (2.10 +/- 0.17).10(-14)C.
Assuntos
Segmento Externo da Célula Bastonete/fisiologia , Animais , Estimulação Elétrica , Técnicas In Vitro , Matemática , Modelos Teóricos , Células Fotorreceptoras/fisiologia , Cianeto de Potássio/farmacologia , Rana ridibunda , Segmento Externo da Célula Bastonete/citologia , Segmento Externo da Célula Bastonete/efeitos dos fármacosRESUMO
Measurements were made on the conductivity of digitonin extracts of frog rhodopsin with and without previous light exposure. The light-dark difference in conductivity is observed at low concentrations of rhodopsin and detergent.
Assuntos
Pigmentos da Retina/metabolismo , Rodopsina/metabolismo , Animais , Digitonina , Condutividade Elétrica , Cinética , Rana pipiens , SoluçõesAssuntos
Radioisótopos de Cálcio , Cálcio/metabolismo , Catarata/metabolismo , Cristalino/metabolismo , Animais , AnurosRESUMO
Retina is an excitable system containing approximately 90% water. As we found that deuteration selectively changes amplitudes and latencies of retina biopotentials, specifically the ON and OFF responses, we used it to probe the role of water in those processes. A study of the retina deuteration kinetics was simultaneously performed. This revealed the existence of at least two retinal water compartments. The data suggested a third compartment also, with a lower motional "degree of freedom," existing where H2O-D2O exchange becomes important only after saturation by D2O of the first two compartments. Correlation of the electrophysiological effects of D2O with the kinetic data suggests that the ON response is related to the first water compartment and the OFF response to the third. The results point to independence on the ON and OFF response mechanisms and, very probably, to their different morphological origins.
