Biomaterial Database

Temperature dependencies of Ca2+ current, Ca(2+)-activated Cl- current and Ca2+ transients in sensory neurones. 1998

J L Kenyon, and H R Goff

Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno 89557, USA. kenyon@physio.unr.edu

We recorded Ca2+ current (ICa) and Ca(2+)-activated Cl- current (ICl(Ca)) in isolated chick dorsal root ganglion neurons. At room temperature, ICl(Ca) is activated by Ca2+ influx (e.g. ICa) or by caffeine-stimulated release of Ca2+ via ryanodine receptors. Warming from room temperature to 37 degrees C increased the amplitude of ICa as well as the amplitude and rate of deactivation of ICl(Ca) activated by Ca2+ influx. In contrast, the activation of ICl(Ca) by caffeine-stimulated release of Ca2+ from intracellular stores abruptly failed between 19 and 28 degrees C. Warning from 22 to 37 degrees C reduced the amplitude of [Ca2+]i transients (measured with Indo-1) in chick neurons by more than 50% and reduced [Ca2+]i transients in mouse neurons by more than 40%. We investigated the role of mitochondria in these phenomena using carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone (FCCP) to inhibit mitochondrial Ca2+ uptake. 1-4 microM FCCP slowed the deactivation of ICa-activated ICl(Ca) at 20 degrees C and at 36 degrees C, having a greater effect at the higher temperature. In the presence of FCCP, the rate of deactivation of ICl(Ca) was relatively insensitive to temperature in this protocol. In contrast, FCCP had little effect on ICl(Ca) activated by caffeine at warmer temperatures (> 22 degrees C) but prolonged ICl(Ca) at cooler temperatures (< 22 degrees C). Thus, we find that warming reduces the ability of Ca2+ release to raise [Ca2+]i increases the effect of mitochondria on the deactivation of ICl(Ca) if ICl(Ca) is activated by Ca2+ influx, and reduces the effect of mitochondria if ICl(Ca) is activated by caffeine-stimulated Ca2+ release.

UI	MeSH Term	Description	Entries
D008928	Mitochondria	Semiautonomous, self-reproducing organelles that occur in the cytoplasm of all cells of most, but not all, eukaryotes. Each mitochondrion is surrounded by a double limiting membrane. The inner membrane is highly invaginated, and its projections are called cristae. Mitochondria are the sites of the reactions of oxidative phosphorylation, which result in the formation of ATP. They contain distinctive RIBOSOMES, transfer RNAs (RNA, TRANSFER); AMINO ACYL T RNA SYNTHETASES; and elongation and termination factors. Mitochondria depend upon genes within the nucleus of the cells in which they reside for many essential messenger RNAs (RNA, MESSENGER). Mitochondria are believed to have arisen from aerobic bacteria that established a symbiotic relationship with primitive protoeukaryotes. (King & Stansfield, A Dictionary of Genetics, 4th ed)	Mitochondrial Contraction,Mitochondrion,Contraction, Mitochondrial,Contractions, Mitochondrial,Mitochondrial Contractions
D009475	Neurons, Afferent	Neurons which conduct NERVE IMPULSES to the CENTRAL NERVOUS SYSTEM.	Afferent Neurons,Afferent Neuron,Neuron, Afferent
D002110	Caffeine	A methylxanthine naturally occurring in some beverages and also used as a pharmacological agent. Caffeine's most notable pharmacological effect is as a central nervous system stimulant, increasing alertness and producing agitation. It also relaxes SMOOTH MUSCLE, stimulates CARDIAC MUSCLE, stimulates DIURESIS, and appears to be useful in the treatment of some types of headache. Several cellular actions of caffeine have been observed, but it is not entirely clear how each contributes to its pharmacological profile. Among the most important are inhibition of cyclic nucleotide PHOSPHODIESTERASES, antagonism of ADENOSINE RECEPTORS, and modulation of intracellular calcium handling.	1,3,7-Trimethylxanthine,Caffedrine,Coffeinum N,Coffeinum Purrum,Dexitac,Durvitan,No Doz,Percoffedrinol N,Percutaféine,Quick-Pep,Vivarin,Quick Pep,QuickPep
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
D002259	Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone	A proton ionophore that is commonly used as an uncoupling agent in biochemical studies.	Carbonyl Cyanide para-Trifluoromethoxyphenylhydrazone,FCCP,(4-(Trifluoromethoxy)phenyl)hydrazonopropanedinitrile,Carbonyl Cyanide p Trifluoromethoxyphenylhydrazone,Carbonyl Cyanide para Trifluoromethoxyphenylhydrazone,Cyanide p-Trifluoromethoxyphenylhydrazone, Carbonyl,Cyanide para-Trifluoromethoxyphenylhydrazone, Carbonyl,p-Trifluoromethoxyphenylhydrazone, Carbonyl Cyanide,para-Trifluoromethoxyphenylhydrazone, Carbonyl Cyanide
D002462	Cell Membrane	The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.	Plasma Membrane,Cytoplasmic Membrane,Cell Membranes,Cytoplasmic Membranes,Membrane, Cell,Membrane, Cytoplasmic,Membrane, Plasma,Membranes, Cell,Membranes, Cytoplasmic,Membranes, Plasma,Plasma Membranes
D002712	Chlorides	Inorganic compounds derived from hydrochloric acid that contain the Cl- ion.	Chloride,Chloride Ion Level,Ion Level, Chloride,Level, Chloride Ion
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.
D004721	Endoplasmic Reticulum	A system of cisternae in the CYTOPLASM of many cells. In places the endoplasmic reticulum is continuous with the plasma membrane (CELL MEMBRANE) or outer membrane of the nuclear envelope. If the outer surfaces of the endoplasmic reticulum membranes are coated with ribosomes, the endoplasmic reticulum is said to be rough-surfaced (ENDOPLASMIC RETICULUM, ROUGH); otherwise it is said to be smooth-surfaced (ENDOPLASMIC RETICULUM, SMOOTH). (King & Stansfield, A Dictionary of Genetics, 4th ed)	Ergastoplasm,Reticulum, Endoplasmic
D013696	Temperature	The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.	Temperatures