Biomaterial Database

The intrinsic intracellular H+ buffering power of snail neurones. 1989

M S Szatkowski, and R C Thomas

Department of Physiology, University of Bristol.

1. We measured intracellular pH (pHi) in snail neurones using pH-sensitive glass microelectrodes. We then calculated the intracellular buffering power (beta i) from the pHi changes associated with the influx or efflux of a variety of weak acids or bases. 2. The weak acid anions butyrate and propionate (20 mM) gave similar values for beta i but those measured using 20 mM-acetate were on average twice as great. 3. Although solutions were nominally CO2-free, blockage of pHi regulation with SITS (4-acetamido-4'-isothiocyanatostilbene-2,2'-disulphonic acid) increased the sizes of the pHi changes upon weak acid addition and removal. The corresponding measured values of beta i were on average 26% lower with SITS than without. 4. With pHi regulation blocked, the use of 2.7% CO2 to measure beta i gave beta i values similar to those measured with butyrate or propionate. These values were about 50% less than those previously measured in snail neurones using CO2. 5. beta i values calculated from the pHi changes due to the removal of 5 mM of the weak bases trimethylamine, procaine and NH4Cl were all similar and comparable to those measured using butyrate or propionate. Removing the influence of pHi regulation on the undershoots after NH4Cl removal was found to decrease the apparent measured values of beta i by 10%. 6. Combining all the data (except the values obtained using CO2 and acetate), and adjusting for the errors due to pHi regulation reducing the sizes of the pHi changes, we found that the mean value for beta i was 10.4 +/- 0.6 mM (+/- S.E.M.) at a mean pHi of 7.36 +/- 0.05. 7. We also investigated the relationship between beta i and pHi using ionophoretic acid injection. By means of step-wise injections, with pHi regulation blocked, we found that at normal pHi levels beta i remained relatively constant. However, at a pHi of less than about 6.8 beta i increased with decreasing pHi.

UI	MeSH Term	Description	Entries
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
D008744	Methylamines	Derivatives of methylamine (the structural formula CH3NH2).
D009474	Neurons	The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.	Nerve Cells,Cell, Nerve,Cells, Nerve,Nerve Cell,Neuron
D011343	Procaine	A local anesthetic of the ester type that has a slow onset and a short duration of action. It is mainly used for infiltration anesthesia, peripheral nerve block, and spinal block. (From Martindale, The Extra Pharmacopoeia, 30th ed, p1016).	Anuject,Geriocaine,Gerokit,Hewedolor-Procain,Lophakomp-Procain N,Novocain,Novocaine,Procain Braun,Procain Jenapharm,Procain Rödler,Procain Steigerwald,Procain curasan,Procaina Serra,Procaine Hydrochloride,Pröcaine chlorhydrate Lavoisier,Röwo Procain,procain-loges,Hydrochloride, Procaine
D011422	Propionates	Derivatives of propionic acid. Included under this heading are a broad variety of acid forms, salts, esters, and amides that contain the carboxyethane structure.	Propanoate,Propanoic Acid,Propionate,Propanoates,Propanoic Acid Derivatives,Propanoic Acids,Propionic Acid Derivatives,Propionic Acids,Acid, Propanoic,Acids, Propanoic,Acids, Propionic,Derivatives, Propanoic Acid,Derivatives, Propionic Acid
D002021	Buffers	A chemical system that functions to control the levels of specific ions in solution. When the level of hydrogen ion in solution is controlled the system is called a pH buffer.	Buffer
D002087	Butyrates	Derivatives of BUTYRIC ACID. Included under this heading are a broad variety of acid forms, salts, esters, and amides that contain the carboxypropane structure.	Butyrate,n-Butyrate,Butanoic Acids,Butyric Acids,Acids, Butanoic,Acids, Butyric,n Butyrate
D005724	Ganglia	Clusters of multipolar neurons surrounded by a capsule of loosely organized CONNECTIVE TISSUE located outside the CENTRAL NERVOUS SYSTEM.
D006372	Helix, Snails	A genus of chiefly Eurasian and African land snails including the principal edible snails as well as several pests of cultivated plants.	Helix (Snails),Snails Helix
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations