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Biomedical subjects

Y Seo

Publications and source records attributed to Y Seo.

At least 181 records · Page 10Linked to original sources
PubMed1984

Effects of Na+ depletion on fluid secretion and levels of phosphorus compounds as measured by 31P-NMR in perfused canine mandibular gland.

The dependency of fluid secretion on extracellular Na+ and the levels of phosphorus compounds were studied in the perfused canine mandibular gland (using 31P-NMR). During control perfusion, the resting levels of creatine phosphate (CP) and ATP were 0.62 +/- 0.05 mmol . kg-1 gland and 0.42 +/- 0.04 mmol . kg-1 (mean +/- S.E., n = 9), respectively. Acetylcholine (Ach; 1 mumol . l-1 for 3 min) induced a salivary secretion and decreased the CP level. When Na+ in the perfusate was completely replaced with Li+, Ach induced only a minimal salivary secretion and no change in the ATP and CP levels. Restitution of Na+ to the perfusion, even without added Ach, caused a decrease in ATP and CP, and a small increase in salivary secretion. These results suggest that the activity of Na+/K+ ATPase is increased inversely via a rise of the intracellular Na+ concentration and that the salivary secretion is induced not only by added secretagogues but by an increase in the Na+ entry without added secretagogues.

Adenosine Triphosphate↗
PubMed1984

In vivo 31P-NMR studies on aerobic recovery of frog muscle following tetanus.

Aerobic recovery after a 60-sec tetanus of skeletal muscle of frog was studied using the in vivo 31P-NMR method with a topical magnetic resonance spectrometer (TMR) at 17 degrees C. Creatine phosphate recovered with a time constant of about 25 min-1. Sugar phosphates increased by the Pasteur effect, and saturated at about 4.5 mmol/kg muscle. The high level of the sugar phosphates was sustained during the following 60 min.

Adenosine Triphosphate↗
PubMed1983

Phosphorus nuclear magnetic resonance of perfused salivary gland.

Phosphorus nuclear magnetic resonance (31P-NMR) was used for the sequential measurement of phosphorus energy metabolites in perfused canine submandibular gland. Under resting conditions, ATP and creatine phosphate levels were 0.42 +/- 0.11 mM and 0.62 +/- 0.16 mM (mean +/- S.D., in nine glands). When perfusion of the gland was stopped, the tissue contents of ATP and creatine phosphate decreased, that of ADP increased and tissue pH decreased. Restarting perfusion led to recoveries of the tissue content of the phosphorus compounds and tissue pH to normal. Acetylcholine administration induced secretion of saliva, decreased the level of ATP, creatine phosphate and tissue pH, and increased the ADP level.

Acetylcholine↗
PubMed1983

Intracellular pH determination by a 31P-NMR technique. The second dissociation constant of phosphoric acid in a biological system.

To evaluate the accuracy of pH determination by 31P-NMR, factors which influence the pK value of phosphate were appraised on the basis of the titration of 1 mM phosphate buffer solution. When the method is used for the determination of cytoplasmic pH, ionic strength is the major factor causing shifts of apparent pK (pK') value, and the magnitude of the shift can be predicted from the ionic strength calculated by means of the Debye-Hückel equation. Ions (Na+, K+, Mg2+, and Ca2+) and salivary protein affected the pK' value by 0.1 to 0.3 units in solution with a given ionic strength depending on the species of ion. The form of the titration curve varied with temperature. Based on these results, the value of 6.75 was obtained with the uncertainty of 0.12 for the intracellular pK' of frog muscle at 24 degrees C.

Animals↗
PubMed1983

A 1H-nuclear magnetic resonance study on lactate and intracellular pH in frog muscle.

High resolution proton magnetic resonance spectra of intact frog muscle, obtained by the selective saturation of water signal with 15 min accumulation, showed well-resolved signals from lactate, carnosine, and other compounds. This technique was used to monitor the changes in lactate content and in intracellular pH which was estimated from the chemical shift of carnosine in muscle. The intracellular pH was estimated to be 7.1 in fresh muscles. Under an anaerobic condition, resting muscle showed a gradual increase in lactate content with intracellular acidification. When the anaerobic muscle was electrically stimulated for 5 sec, a transient acceleration of the lactate production and the intracellular acidification was observed. The intracellular buffer value was estimated to be 27 mEq/(pH X kg muscle), based on the pH change due to the increase in lactate content.

Animals↗
PubMed1982

Application of pulsed-gradient 31P NMR on frog muscle to measure the diffusion rates of phosphorus compounds in cells.

Pulsed-gradient 31P NMR was used to measure the diffusion rates of phosphorus compounds in aqueous solution and in living muscles. The diffusion rates of creatine phosphate and inorganic phosphate in intact frog muscle cells were reduced by a factor of approximately 2 from those in aqueous solution, which suggests that the apparent intracellular viscosity is approximately 2 times larger than in aqueous solution.

Animals↗
PubMed1981

High-resolution proton magnetic resonance spectra of muscle.

High-resolution proton magnetic resonance spectra of intact muscles of frog and rat were obtained with selective saturation of the water signal. The spectra consisted of the superposition of a broad component and a high-resolution portion. The line width of the former was about 5 ppm and is assumed to originate from the protons of the macromolecules in muscle. The high-resolution portion showed well-resolved signals arising from creatine phosphate, creatine, carnosine, lactate and lipids. It is suggested that this technique could be used to monitor the intracellular pH by measuring the chemical shift of carnosine and the lipid consumption due to muscular contraction. When the spectrum of 31P-NMR is prepared simultaneously, the ratio of creatine phosphate to total creatine can also be determined.

Animals↗