Biomaterial Database

The effects of quinidine on sodium-dependent calcium efflux in isolated rod photoreceptors of the salamander retina. 1990

L Lagnado, and P A McNaughton

Physiological Laboratory, Cambridge, UK.

The effect of quinidine on the membrane current generated by the Na:Ca, K exchange has been investigated in the outer segment of isolated rod photoreceptors from the retina of the larval tiger salamander. The inward exchange current associated with the efflux of Ca2+ was selectively recorded by introducing a Ca2+ load through the light-sensitive channels, and then shutting these channels with a bright light. Quinidine (20-1000 microM) reduced the magnitude of the exchange current and slowed its decay during the removal of a Ca2+ load. Quinidine did not alter the form of the relation between the exchange current and the total concentration of exchangeable calcium remaining within the outer segment. [Ca]T, showing that it does not change the affinity of the exchange mechanism for internal Ca2+. The relation between exchange current inhibition and the quinidine concentration could be described by a simple Michaelis relation with a Ki of 287 microM and a maximum inhibition of 50%. The incomplete block of the Na:Ca, K exchange current by quinidine shows that it does not act by simple competition with external Na+, and suggests that the inhibition of the exchange by quinidine may be non-specific.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
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
D011188	Potassium	An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.
D011802	Quinidine	An optical isomer of quinine, extracted from the bark of the CHINCHONA tree and similar plant species. This alkaloid dampens the excitability of cardiac and skeletal muscles by blocking sodium and potassium currents across cellular membranes. It prolongs cellular ACTION POTENTIALS, and decreases automaticity. Quinidine also blocks muscarinic and alpha-adrenergic neurotransmission.	Adaquin,Apo-Quinidine,Chinidin,Quincardine,Quinidex,Quinidine Sulfate,Quinora,Apo Quinidine,Sulfate, Quinidine
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
D002118	Calcium	A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
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
D012964	Sodium	A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.	Sodium Ion Level,Sodium-23,Ion Level, Sodium,Level, Sodium Ion,Sodium 23
D014562	Urodela	An order of the Amphibia class which includes salamanders and newts. They are characterized by usually having slim bodies and tails, four limbs of about equal size (except in Sirenidae), and a reduction in skull bones.	Amphiuma,Caudata,Eel, Congo,Salamanders,Congo Eel,Congo Eels,Eels, Congo,Salamander
D015056	1-Methyl-3-isobutylxanthine	A potent cyclic nucleotide phosphodiesterase inhibitor; due to this action, the compound increases cyclic AMP and cyclic GMP in tissue and thereby activates CYCLIC NUCLEOTIDE-REGULATED PROTEIN KINASES	3-Isobutyl-1-methylxanthine,Isobutyltheophylline,IBMX,1 Methyl 3 isobutylxanthine,3 Isobutyl 1 methylxanthine