Biomaterial Database

Anions modulate cation-induced responses of single units of the frog glossopharyngeal nerve. 1995

Y Kitada

Department of Physiology, Okayama University Dental School, Japan.

Fibers of the frog glossopharyngeal nerve that are sensitive to water stimulation also respond to Ca, Mg and Na salts. During stimulation with a salt, the cation and the anion are applied together and the anion could influence the response to the cation. We examined this interaction using single unit recordings at the level of fungiform papilla. Nerve impulses of large amplitude were recorded in response to the stimulation of adjacent papillae with increasing concentrations of various Ca, Mg and Na salts. For a given cation, the elicited spike frequency depended on the anion. For example, the responses of single fibers to Ca2+ concentrations above 0.1 mM were maximal with CaSO4 and minimal with Ca(SCN)2. The rank order of efficiency was CaSO4 > CaCl2 = CaBr2 = Ca(NO3)2 > Ca(SCN)2 for Ca2+ ions at 5 mM. The effects of these anions were reversed for Mg and Na salts, the rank orders being Mg(SCN)2 > Mg(NO3)2 > MgBr2 = MgCl2 > MgSO4, for Mg2+ ions at 200 mM, and NaSCN > NaI > NaNO3 > NaBr > NaCl >> NaF = Na2SO4, for Na+ ions at 500 mM. All these sequences correspond to the lyotropic rank order of the anions. In stimulation by a mixture of Ca and Na salts, which have different rank orders with respect to anions, either the response to Ca2+ ions or the response to Na+ ions could be eliminated as a result of mutual antagonism between Ca2+ and Na+ ions. In this case, the rank order of anions was dependent only on the cation that was able to exert a stimulatory effect in the mixture. Threshold concentrations for Ca, Mg and Na salts are influenced by cationic properties, but not by anionic properties. We hypothesize that anions can modulate the efficacy of cation transduction by binding to a membrane element that interacts with each of the three distinct receptors for Ca2+, Mg2+ and Na+ ions without altering the affinities of these receptors for the respective cations. The present results cannot be interpreted in terms of permeability of the apical membrane to anions and changes in surface potential on the apical membrane. The possibility is discussed that an anion-selective paracellular pathway between taste cells is responsible for the effect of anions on the cation-induced response.

UI	MeSH Term	Description	Entries
D007477	Ions	An atom or group of atoms that have a positive or negative electric charge due to a gain (negative charge) or loss (positive charge) of one or more electrons. Atoms with a positive charge are known as CATIONS; those with a negative charge are ANIONS.
D008274	Magnesium	A metallic element that has the atomic symbol Mg, atomic number 12, and atomic weight 24.31. It is important for the activity of many enzymes, especially those involved in OXIDATIVE PHOSPHORYLATION.
D011892	Rana catesbeiana	A species of the family Ranidae (true frogs). The only anuran properly referred to by the common name "bullfrog", it is the largest native anuran in North America.	Bullfrog,Bullfrogs,Rana catesbeianas,catesbeiana, Rana
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
D002412	Cations	Positively charged atoms, radicals or groups of atoms which travel to the cathode or negative pole during electrolysis.	Cation
D002712	Chlorides	Inorganic compounds derived from hydrochloric acid that contain the Cl- ion.	Chloride,Chloride Ion Level,Ion Level, Chloride,Level, Chloride Ion
D005930	Glossopharyngeal Nerve	The 9th cranial nerve. The glossopharyngeal nerve is a mixed motor and sensory nerve; it conveys somatic and autonomic efferents as well as general, special, and visceral afferents. Among the connections are motor fibers to the stylopharyngeus muscle, parasympathetic fibers to the parotid glands, general and taste afferents from the posterior third of the tongue, the nasopharynx, and the palate, and afferents from baroreceptors and CHEMORECEPTOR CELLS of the carotid sinus.	Cranial Nerve IX,Ninth Cranial Nerve,Cranial Nerve IXs,Cranial Nerve, Ninth,Cranial Nerves, Ninth,Glossopharyngeal Nerves,Nerve, Glossopharyngeal,Nerve, Ninth Cranial,Nerves, Glossopharyngeal,Nerves, Ninth Cranial,Ninth Cranial Nerves
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
D000838	Anions	Negatively charged atoms, radicals or groups of atoms which travel to the anode or positive pole during electrolysis.	Anion
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