Biomaterial Database

Direct measurement of intracellular pH and buffering power in smooth muscle cells of guinea-pig vas deferens. 1984

C C Aickin

A double-barrelled, pH-sensitive micro-electrode suitable for use in mammalian smooth muscle has been developed. It was shown to be unaffected by alteration of Na, K, Ca, Mg, Cl or CO2, and yielded the same results in mouse soleus muscle as had been obtained previously with the recessed-tip pH-sensitive glass electrode ( Aickin & Thomas, 1977 a). Intracellular pH (pHi) of the surface cells of guinea-pig vas deferens was 7.06 +/- 0.09 (n = 52, S.D. of an observation) in Krebs solution equilibrated with 3% CO2 at pH 7.35. The membrane potential (Em) was -65.5 +/- 6.7 mV. Thus pHi is about 0.8 units more alkaline than that predicted if H+ ions were passively distributed across the cell membrane. Alteration of extracellular pH (pHo) at constant CO2 caused a smaller change in pHi, by about 40% of that in pHo. The change was complete in 6-12 min and was of a similar magnitude whether the alteration was made in the continual presence or absence of CO2. Alteration of the CO2 level at constant pHo caused a rapid change in pHi followed by a slower, complete recovery. Thus the same stabilized pHi was recorded in different CO2-containing solutions. When CO2 was removed, the expected intracellular alkalinization was reduced or even obscured by a considerable acidification. pHi then stabilized at a mean value of 6.81 +/- 0.11 (n = 18) with an Em of -60.8 +/- 8.2 mV. The acidification expected on readmission of CO2 was minimized or obscured by a rapid recovery of pHi to the value previously recorded in CO2-containing solutions. A simultaneous increase in CO2 and decrease in pHo caused a rapid fall in pHi which increased in magnitude with decreasing pHo. This fall was followed by an incomplete recovery when pHo was above about 6.8 (but below 7.35), by no further change in pHi when pHo was about 6.7 and by a slow, continued fall in pHi when pHo was below 6.7. The intrinsic buffering power was calculated from the pHi changes observed on alteration of CO2. The values obtained increased in parallel with the extent to which pHi recovered following the imposed change, probably explained by an inseparable contribution to the minimization of the change by transport processes.(ABSTRACT TRUNCATED AT 400 WORDS)

UI	MeSH Term	Description	Entries
D008297	Male		Males
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
D008839	Microelectrodes	Electrodes with an extremely small tip, used in a voltage clamp or other apparatus to stimulate or record bioelectric potentials of single cells intracellularly or extracellularly. (Dorland, 28th ed)	Electrodes, Miniaturized,Electrode, Miniaturized,Microelectrode,Miniaturized Electrode,Miniaturized Electrodes
D009130	Muscle, Smooth	Unstriated and unstriped muscle, one of the muscles of the internal organs, blood vessels, hair follicles, etc. Contractile elements are elongated, usually spindle-shaped cells with centrally located nuclei. Smooth muscle fibers are bound together into sheets or bundles by reticular fibers and frequently elastic nets are also abundant. (From Stedman, 25th ed)	Muscle, Involuntary,Smooth Muscle,Involuntary Muscle,Involuntary Muscles,Muscles, Involuntary,Muscles, Smooth,Smooth Muscles
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
D002245	Carbon Dioxide	A colorless, odorless gas that can be formed by the body and is necessary for the respiration cycle of plants and animals.	Carbonic Anhydride,Anhydride, Carbonic,Dioxide, Carbon
D006168	Guinea Pigs	A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.	Cavia,Cavia porcellus,Guinea Pig,Pig, Guinea,Pigs, Guinea
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
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
D014649	Vas Deferens	The excretory duct of the testes that carries SPERMATOZOA. It rises from the SCROTUM and joins the SEMINAL VESICLES to form the ejaculatory duct.	Ductus Deferens,Deferens, Ductus,Deferens, Vas