Biomaterial Database

Decoupling of horizontal cells in carp and turtle retinae by intracellular injection of cyclic AMP. 1989

E Miyachi, and M Murakami

Department of Physiology, Keio University School of Medicine, Tokyo, Japan.

1. Horizontal cells are electrically coupled through gap junctions. This is a disadvantage in elucidating the membrane properties of the cells. In order to block gap junctions, adenosine 3',5'-cyclic monophosphate (cyclic AMP) or its analogues, dibutyryl cyclic AMP and 8-bromo cyclic AMP, were ionophoretically injected into horizontal cells of the carp or turtle retina. 2. Before injection of the chemicals the input resistance of the cell was so low as to be unmeasurable, because the applied current leaked through gap junctions. After injection, however, the input resistance was significantly increased. 3. After the injection dye-coupling between horizontal cells was not observed when examined by intracellular injection of Lucifer Yellow dye, supporting the idea that high concentrations of intracellular cyclic AMP block gap junctions. 4. In this situation responses to light delivered to the receptive field centre were increased in amplitude, while responses to light delivered to the receptive field surround were greatly diminished. 5. After injection horizontal cells were readily polarized by conventional intracellular current injection. The hyperpolarizing light responses in carp and turtle luminosity-type cells (H1 cells) could be reversed by depolarizing the horizontal cells, and the reversal potentials were estimated to be about 0 mV. In addition, the resistance increase which accompanied the hyperpolarizing light responses could be detected. 6. In turtle biphasic chromaticity-type horizontal cells (H2 cells), hyperpolarizing light responses to shorter wavelengths and depolarizing ones to longer wavelengths could be reversed by depolarizing the horizontal cells. Both responses have almost the same reversal potential at about 0 mV. The membrane resistance changes associated with light responses were also detected; the resistance increased during the hyperpolarizing response, while it decreased during the depolarizing response. These observations suggest that the ionic mechanisms of both responses are probably the same, irrespective of their polarities.

UI	MeSH Term	Description	Entries
D007365	Intercellular Junctions	Direct contact of a cell with a neighboring cell. Most such junctions are too small to be resolved by light microscopy, but they can be visualized by conventional or freeze-fracture electron microscopy, both of which show that the interacting CELL MEMBRANE and often the underlying CYTOPLASM and the intervening EXTRACELLULAR SPACE are highly specialized in these regions. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p792)	Cell Junctions,Cell Junction,Intercellular Junction,Junction, Cell,Junction, Intercellular,Junctions, Cell,Junctions, Intercellular
D012160	Retina	The ten-layered nervous tissue membrane of the eye. It is continuous with the OPTIC NERVE and receives images of external objects and transmits visual impulses to the brain. Its outer surface is in contact with the CHOROID and the inner surface with the VITREOUS BODY. The outer-most layer is pigmented, whereas the inner nine layers are transparent.	Ora Serrata
D002347	Carps	Common name for a number of different species of fish in the family Cyprinidae. This includes, among others, the common carp, crucian carp, grass carp, and silver carp.	Carassius carassius,Crucian Carp,Cyprinus,Grass Carp,Carp,Ctenopharyngodon idellus,Cyprinus carpio,Hypophthalmichthys molitrix,Koi Carp,Silver Carp,Carp, Crucian,Carp, Grass,Carp, Koi,Carp, Silver,Carps, Crucian,Carps, Grass,Carps, Silver,Crucian Carps,Grass Carps,Silver Carps
D003530	Cyprinidae	A family of freshwater fish comprising the minnows or CARPS.	Barbels,Chub,Dace,Minnows,Roach (Fish),Shiner,Tench,Tinca,Barbus,Rutilus rutilus,Tinca tinca,Chubs,Shiners,Tinca tincas,tinca, Tinca
D003994	Bucladesine	A cyclic nucleotide derivative that mimics the action of endogenous CYCLIC AMP and is capable of permeating the cell membrane. It has vasodilator properties and is used as a cardiac stimulant. (From Merck Index, 11th ed)	Dibutyryl Adenosine-3',5'-Monophosphate,Dibutyryl Cyclic AMP,(But)(2) cAMP,Bucladesine, Barium (1:1) Salt,Bucladesine, Disodium Salt,Bucladesine, Monosodium Salt,Bucladesine, Sodium Salt,DBcAMP,Dibutyryl Adenosine 3,5 Monophosphate,N',O'-Dibutyryl-cAMP,N(6),0(2')-Dibutyryl Cyclic AMP,AMP, Dibutyryl Cyclic,Adenosine-3',5'-Monophosphate, Dibutyryl,Cyclic AMP, Dibutyryl,Dibutyryl Adenosine 3',5' Monophosphate,Disodium Salt Bucladesine,Monosodium Salt Bucladesine,N',O' Dibutyryl cAMP,Sodium Salt Bucladesine
D004594	Electrophysiology	The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.
D000242	Cyclic AMP	An adenine nucleotide containing one phosphate group which is esterified to both the 3'- and 5'-positions of the sugar moiety. It is a second messenger and a key intracellular regulator, functioning as a mediator of activity for a number of hormones, including epinephrine, glucagon, and ACTH.	Adenosine Cyclic 3',5'-Monophosphate,Adenosine Cyclic 3,5 Monophosphate,Adenosine Cyclic Monophosphate,Adenosine Cyclic-3',5'-Monophosphate,Cyclic AMP, (R)-Isomer,Cyclic AMP, Disodium Salt,Cyclic AMP, Monoammonium Salt,Cyclic AMP, Monopotassium Salt,Cyclic AMP, Monosodium Salt,Cyclic AMP, Sodium Salt,3',5'-Monophosphate, Adenosine Cyclic,AMP, Cyclic,Adenosine Cyclic 3',5' Monophosphate,Cyclic 3',5'-Monophosphate, Adenosine,Cyclic Monophosphate, Adenosine,Cyclic-3',5'-Monophosphate, Adenosine,Monophosphate, Adenosine Cyclic
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
D014426	Turtles	Any reptile including tortoises, fresh water, and marine species of the order Testudines with a body encased in a bony or cartilaginous shell consisting of a top (carapace) and a bottom (plastron) derived from the ribs.	Sea Turtles,Terrapins,Tortoises,Sea Turtle,Terrapin,Tortoise,Turtle,Turtle, Sea,Turtles, Sea
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