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Biomedical subjects

A Watanabe

Publications and source records attributed to A Watanabe.

At least 1,099 records · Page 61Linked to original sources
PubMed1976

Effects of intracellular pH on plateau formation following the action potential of squid giant axons.

When squid giant axons were intracellularly perfused for about 10 min with 100 mM K+ solutions containing Pronase or Protease Type VII at a concentration of 0.1-0.5 mg/ml, the action potential developed a long-lasting plateau. The plateau persisted after switching to an enzyme-free solution at standard pH (7.3 +/- 0.1) as the intracellular perfusate. The plateau was promptly and completely suppressed when the intracellular pH was lowered below 6.5. Upon increase of pH again to the standard level, the plateau promptly reappeared. With alkaline intracellular pH plateau formation was enhanced. Lowering the pH of the extracellular medium to 5 did not influence the plateau. The duration of the action potential under bi-ionic conditions (inside Cs+, outside Ca++) decreased with low intracellular pH and increased with high intracellular pH. The plateau duration of the action potential from axons intracellularly perfused with solutions containing 10 mM tetraethylammonium also decreased with low intracellular pH and increased with high intracellular pH. The underlying mechanisms for the pH effects remain to be explored.

Action Potentials↗
PubMed1976

Differential mechanisms of increased alpha 1-fetoprotein production in rats following carbon tetrachloride injury and partial hepatectomy.

Possible differences in the mechanisms of increased alpha1-fetoprotein (AFP) production following carbon tetrachloride (CCl4) intoxication and partial hepatectomy were studied with 5-week-old rats at the time of sacrifice. The maximum level of serum AFP reached in 4 days after a single dose of CCl4 was much higher than that after partial hepatectomy, although the incorporation of [3H]thymidine into liver DNA increased nearly to the same extent by either of these treatments. In the remnant after partial hepatectomy, the DNA synthesis that was further accelerated by treatment with a lower dose of thioacetamide was not associated with any further increases of serum AFP levels. However, CCl4 given to partially hepatectomized rats had an additive effect on increased AFP levels. The increases of serum AFP concentrations in CCl4-injured rats had an additive effect on increased AFP levels. The increases of serum AFP concentrations in CCl4-injured rats were depressed by Mitomycin C given in vivo, whereas the increases in partially hepatectomized rats were not. Treatment with 8-azaguanine inhibited both increase of serum AFP levels, although the inhibition was much less or was insignificant in partially hepatectomized rats. These results suggest that existence of different underlying mechanisms of the increased AFP production for the two experimental conditions.

Animals↗
PubMed1976

Increased alpha1-fetoprotein production in rat liver injuries induced by various hepatotoxins.

Serum alpha1-fetoprotein (AFP) concentration in 5-week-old rats was measured by the radioimmunoassay technique after a single administration of various hepatotoxins. Marked elevation of serum AFP concentrations occurred in rats treated with carbon tetrachloride, thioacetamide, D-galactosamine, allyl alcohol, allyl formate, and ethionine in 4 days of these treatments. The increased production of AFP appeared to be correlated with the induction of liver glucose-6-phosphate dehydrogenase (G-6-PD) among biochemical parameters studied for hepatocellular injuries. However, the difference in time courses of the increase in liver G-6-PD activity and serum AFP level following CC14 treatment suggested that the increased production of serum AFP and the induction of G-6-PD in injured liver were caused by closely related but different mechanisms. Pretreatment of CC14-injured rats with N,N'-diphenyl-p-phenylenediamine or aminoacetonitrile was effective not only in lowering the increased level of serum AFP and liver G-6-PD but also in preventing liver cell necrosis and steatosis induced by CC14. Treatment with a lower dose of thioacetamide resulted in littel elevation of serum AFP and liver G-6-PD with a markedly increased incorporation of 3H-thymidine into liver DNA without any evidence of liver injury. On the other hand, the administration of ethionine, which caused little necrosis of liver cells, produced increase in both serum AFP and liver G-6-PD levels with an only small increase of hepatic DNA synthesis compared to those following thioacetamide as well as CC14. These results suggest that the elevation of serum AFP is not directly related to the stimulation of hepatic DNA synthesis. Some additional mechanisms of specific gene amplification for AFP, which is geared to hepatic injury per se, appear to play a major role in the increased AFP production in injured liver.

Aminoacetonitrile↗
PubMed1976

Effects of iodoacetate and anoxia on phosphate metabolism in isolated perfused rat hearts.

When perfused with a solution equilibrated with 95% N2 and 5% CO2, the isolated rat heart was gradually depressed but continued to beat for longer than 30 min. Creatine phosphate content strikingly decreased, but lactate content was markedly elevated. When perfused with a fully oxygenated solution containing 0.5 mM of sodium iodoacetate (IAA) of the myocardial contractile force was almost unaltered and the heart rate decreased slightly within 10 min. Thereafter, the heart rate rapidly decreased, and soon cardiac arrest followed. Myocardial content of high-energy phosphates still remained at a considerably high level. The heart arrested by IAA responded to electrical stimulation, contracted and high-energy phosphates were well utilized. Addition of lactate to an oxygenated perfusate containing IAA improved myocardial performance. Citrate and palmitate did not restore the IAA-treated cardiac impairment. The results show that IAA disturbed cardiac conduction more markedly than contractility by blocking cytoplasmic glycolysis and that lactate, unlike citrate and palmitate, produced enough energy to recover cardiac activities in IAA-treated hearts.

Animals↗
PubMed1975

Microheterogeneity of rat alpha-fetoprotein.

A purified and homogeneous preparation of rat AFP, as judged by both electrophoresis on Cellogel and immunoelectrophoresis, was separated into two components, AFPa and AFPb, by disc electrophoresis on 7% polyacrylamide gel. These two components had a definite difference in electrostatic net charge and gave only a single band on SDS-electrophoresis. Immunological reactivity or electrophoretic separation or mobility of the two components could be altered by treatment with either sulfhydryl inhibitors or reducing agents but not by treatment with protein denaturants. Electrophoresis of neuraminidase-treated AFP on 5% polyacrylamide gel yielded clearly separable, slower moving four to six and finally two components depending on the time of incubation with neuraminidase. The time-dependent conversion of faster into slower migrating components of both AFPa and AFPb upon neuraminidase treatment was confirmed by reelectrophoresis of separated and similarly treated AFPa and AFPb. Two bands of sialized or desialized AFP were also observed on isoelectric focusing. Both AFPa and AFPb treated with and without neuraminidase gave single fused precipitin lines against the antiserum in Ouchterlony double-diffusion analysis. On the basis of the changes in electrophoretic mobilities of the intermediates following neuraminidase treatment, AFPa and AFPb were estimated to have at least 2.5 and 4.5 molecules of sialic acid per molecule, respectively.

Animals↗
PubMed1975

Undifferentiated patterns of key glycolytic and gluconeogenic enzymes in epithelial cell lines derived from rat liver.

Established epithelial cell lines derived from livers of 7-day (B, B-R, B-3-4-7, J-C-1, J-C-13, J-5-2-1, E-C-4 and E-C-7) and adult (AL-2, AL-3, AL-4, AL-5 and AL-6) rats were analyzed for hexokinase (HK), pyruvate kinase (PK), glucose 6-phosphate dehydrogenase (G6PD), 6-phosphogluconate dehydrogenase (6PGD), glucose 6-phosphatase (G6Pase) and fructose 1,6-diphosphatase (FDPase). None of the cell lines showed appreciable activities of adult type liver enzymes (HK Type IVs (glucokinase), PK Type L, G6Pase and FDPase). On the contrary, the activities of fetal type liver enzymes (HK Types I and II, PK Type M2 and G6PD) increased markedly as compared with dispersed cells or tissues of adult liver. 6PGD gave minimum changes in activity, and the 6PGD/G6PD ratio decreased consistently. HK Type III was found only in J-C-13, AL-5 and AL-6, while HK Type IVf (high Km) was present in all the cell lines examined. Possible explanations for the undifferentiated patterns of carbohydrate-metabolizing enzymes in the established cell lines, which have several evidence of hepatocyte origin, are presented.

Alcohol Oxidoreductases↗
PubMed1975

Microheterogeneity of rat alpha-fetoprotein.

A purified and homogeneous preparation of rat alpha-fetoprotein (AFP) was separated into two components, AFPa and AFPb, by polyacrylamide gel electrophoresis. These two components had a definite difference in electrostatic net charge and gave only a single band on sodium dodecyl sulfate-electrophoresis. Neuraminidase-treated AFP gave clearly separable, slower moving four to six and finally two components depending on the time of incubation with neuraminidase. The time-dependent conversion of each AFPa and AFPb into slower migrating components upon neuraminidase treatment was confirmed by re-electrophoresis of separated and similarly treated AFPa and AFPb.

Animals↗
PubMed1975

Purification and immunochemical characterization of alpha-fetoprotein from rat fetal serum and liver.

Two alpha1-globulin bands of fetal serum with relative mobilities against bromophenol blue of 0.55 and 0.58 on 7% polyacrylamide gel electrophoresis reacted with a monospecific rabbit antiserum to alpha-fetoprotein (AFP). The former globulin band was clearly detected in the fetal liver supernatant. AFP was immunochemically purified from both the fetal serum and liver, and their electrophoretic and immunochemical properties were compared. Liver AFP purified by immunoadsorbent column yielded electrophoretic mobilities and relative amounts of the two electrophoretically distinct components identical with the purified serum AFP. The immunological reactivity of the two components of the purified preparations from serum and liver against the monospecific anti-AFP serum was also indistinguishable. After the removal of the sialic acid residues from purified serum and liver AFP by treatment with neuraminidase for 6 to 12 hr, disc electrophoretic patterns on 5% polyacrylamide gel and immunoelectrophoretic patterns of the treated AFP were found to be closely similar in both preparations. It may be possible to conclude that serum and liver AFP are structurally indistinguishable and probably identical.

Alpha-Globulins↗