Biomaterial Database

Electrical responses of rods in the retina of Bufo marinus. 1977

L Cervetto, and E Pasino, and V Torre

1. Intracellular responses to flashes and steps of light have been recorded from the outer segment and the cell body of rods in the retina of the Bufo marinus. The identification of the origin of recorded responses has been confirmed by intracellular marking.2. Responses to flashes delivered in darkness or superimposed on a background were analysed. Responses recorded from outer segments conform to the principle of ;spectral univariance'. The shape of the response is not affected by enlarging the spot diameter from 150 to 1000 mum.3. The membrane potential measured in darkness at the outer segments varied from -15 to -25 mV. Injection of steady hyperpolarizing currents increases the size of the response to light; depolarizing currents reduce the response. The mean value of the input resistance is 97 +/- 30 MOmega in darkness and increases by 20-30% during illumination.4. The responses obtained from the cell body of rods have the same shape, time course and spectral sensitivity of those recorded at the outer segment. Injection of steady current at the cell body produces different effects than at the outer segment: hyperpolarizing currents reduce the amplitude of the response to light; depolarizing currents increase the response.5. The experimental data are fitted according to a model similar to that used to describe the responses of turtle cones (Baylor & Hodgkin, 1974; Baylor, Hodgkin & Lamb, 1974a, b).6. The model reproduces the electrical responses of the rod outer segment to a variety of stimuli: (a) brief flashes and steps of light in dark adapted conditions; (b) bright flashes superimposed on background illuminations; (c) pairs of flashes delivered at different time intervals. Responses to hyperpolarizing steps of current are also reproduced by the model.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008433	Mathematics	The deductive study of shape, quantity, and dependence. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)	Mathematic
D008564	Membrane Potentials	The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).	Resting Potentials,Transmembrane Potentials,Delta Psi,Resting Membrane Potential,Transmembrane Electrical Potential Difference,Transmembrane Potential Difference,Difference, Transmembrane Potential,Differences, Transmembrane Potential,Membrane Potential,Membrane Potential, Resting,Membrane Potentials, Resting,Potential Difference, Transmembrane,Potential Differences, Transmembrane,Potential, Membrane,Potential, Resting,Potential, Transmembrane,Potentials, Membrane,Potentials, Resting,Potentials, Transmembrane,Resting Membrane Potentials,Resting Potential,Transmembrane Potential,Transmembrane Potential Differences
D010786	Photoreceptor Cells	Specialized cells that detect and transduce light. They are classified into two types based on their light reception structure, the ciliary photoreceptors and the rhabdomeric photoreceptors with MICROVILLI. Ciliary photoreceptor cells use OPSINS that activate a PHOSPHODIESTERASE phosphodiesterase cascade. Rhabdomeric photoreceptor cells use opsins that activate a PHOSPHOLIPASE C cascade.	Ciliary Photoreceptor Cells,Ciliary Photoreceptors,Rhabdomeric Photoreceptor Cells,Rhabdomeric Photoreceptors,Cell, Ciliary Photoreceptor,Cell, Photoreceptor,Cell, Rhabdomeric Photoreceptor,Cells, Ciliary Photoreceptor,Cells, Photoreceptor,Cells, Rhabdomeric Photoreceptor,Ciliary Photoreceptor,Ciliary Photoreceptor Cell,Photoreceptor Cell,Photoreceptor Cell, Ciliary,Photoreceptor Cell, Rhabdomeric,Photoreceptor Cells, Ciliary,Photoreceptor Cells, Rhabdomeric,Photoreceptor, Ciliary,Photoreceptor, Rhabdomeric,Photoreceptors, Ciliary,Photoreceptors, Rhabdomeric,Rhabdomeric Photoreceptor,Rhabdomeric Photoreceptor Cell
D002024	Bufo marinus	A species of the true toads, Bufonidae, becoming fairly common in the southern United States and almost pantropical. The secretions from the skin glands of this species are very toxic to animals.	Rhinella marina,Toad, Giant,Toad, Marine,Giant Toad,Giant Toads,Marine Toad,Marine Toads,Toads, Giant,Toads, Marine
D004553	Electric Conductivity	The ability of a substrate to allow the passage of ELECTRONS.	Electrical Conductivity,Conductivity, Electric,Conductivity, Electrical
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D066298	In Vitro Techniques	Methods to study reactions or processes taking place in an artificial environment outside the living organism.	In Vitro Test,In Vitro Testing,In Vitro Tests,In Vitro as Topic,In Vitro,In Vitro Technique,In Vitro Testings,Technique, In Vitro,Techniques, In Vitro,Test, In Vitro,Testing, In Vitro,Testings, In Vitro,Tests, In Vitro,Vitro Testing, In