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Volume 93 (1989)
- Issue 6 Pages 315-
- Issue 5 Pages 271-
- Issue 4 Pages 203-
- Issue 3 Pages 89-
- Issue 2 Pages 29-
- Issue 1 Pages 7-
Volume 93, Issue 5
Displaying 1-4 of 4 articles from this issue
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Ryuichi KATO, Nobuyuki SASAKAWA1989 Volume 93 Issue 5 Pages 271-281
Published: 1989
Released on J-STAGE: February 20, 2007
JOURNAL FREE ACCESSCultured adrenal chromaffin cells are regarded as a suitable system for studying the regulatory mechanism of “stimulus-secretion coupling”. Indeed, the term “stimulussecretion coupling” was originally coined by Douglas and Rubin for the chromaffin cells. Although it has been suggested that calcium plays a central role in this coupling process, there still remain many important and unresolved issues on the molecular mechanisms of “stimulus-secretion coupling” such as (1) the regulatory mechanisms of the calcium uptake, (2) the mechanism by which calcium entry into the cell induces membrane fusion and exocytosis, and (3) the roles of phospholipase C and C-kinase in mediating intracellular calcium homeostasis and catecholamine secretion. In this review, roles of intracellular calcium and inositol phosphate formation in “stimulus-secretion coupling” in cultured bovine adrenal chromaffin cells are discussed, mainly on the basis of the biochemical and pharmacological differences between agonist and potassium depolarization-induced cellular responses.View full abstractDownload PDF (8464K) -
Kazuko NONAKA, Akira UENO1989 Volume 93 Issue 5 Pages 283-293
Published: 1989
Released on J-STAGE: February 20, 2007
JOURNAL FREE ACCESSWe have described and criticized the methods, techniques and materials used in our laboratory to obtain arterial and venous pressures, arterial and venous blood flows, cardiac output, internal diameter and pressure of the left ventricle, ECG and vascular diameters in unanesthetized and unrestrained dogs using both radiotelemetering systems and a direct wire connecting system.View full abstractDownload PDF (9541K) -
I. Effects of bifemelane on the function of neurotransmission-related enzymes and receptors in rat brainToru EGASHIRA, Takayuki NAGAI, Yoshihira KIMBA, Ritsuko TAKANO, Toshio ...1989 Volume 93 Issue 5 Pages 295-304
Published: 1989
Released on J-STAGE: February 20, 2007
JOURNAL FREE ACCESSWe examined neurochemically the effects of bifemelane (BF) on muscarinic ACh (mACh-R) and /3-adrenergic receptors (β-AdR) and imipramine binding sites and the activities of acetylcholinesterase (AChE), choline acetyltransferase (CAT) and monoamine oxidase (MAO) in the P2 fractions of rat brain, ex vivo and in vitro. Male rats were given daily injections of 10, 30 mg/kg BF, p.o., for a period of 4 weeks. The Kd and Bmax values for mACh-R in the rat forebrain by administration of 10, 30 mg/kg BF decreased significantly compared with that of the control, although the Kd and Bmax values for β-AdR and imipramine binding sites were almost identical. The Km and Vmax values of A and B-form MAO decreased in rats that had been administered 30 mg/kg BF for 4 weeks. The binding of 3H-QNB (quinuclidinyl benzilate) on mACh-R, 125I-CYP (iodocyanopindolol) on β-AdR and 3H-imipramine on imipramine binding sites decreased by 60, 20 and 70% in the presence of 1 μM BF, respectively, while the addition of 1 μM BF inhibited MAO activity by about 50%. However, CAT and AChE activities were not inhibited by BF.View full abstractDownload PDF (7447K) -
Shigeki FUJISAWA, Keiko SHIMATANI, Hiroaki YAMADA, Yutaka HIRONAKA1989 Volume 93 Issue 5 Pages 305-314
Published: 1989
Released on J-STAGE: February 20, 2007
JOURNAL FREE ACCESSThe beneficial effect of LC-80 in the therapy for organic acidemias, especially propionic acidemia and methylmalonic acidemia, was compared with those of its optical isomers, d-carnitine chloride (d-isomer) and dl-carnitine chloride (dl-isomer) in rat liver mitochondria. LC-80 at concentrations of 5 and 10 mM did not inhibit the mitochondrial function, while the d-isomer at a concentration of 5 mM significantly reduced the respiratory control ratio (RCR) of mitochondria. In addition, the dl-isomer at concentrations of 10 and 20 mM also significantly reduced RCR in a concentration-dependent manner. Thus, it seems likely that the d-isomer inhibits the mitochondrial function. On the other hand, the inhibition of mitochondrial function induced by a preincubation with propionate (4.76 mM) was significantly reversed by LC-80 (5 and 10 mM) in a concentration-dependent manner, while the d-isomer (5 mM) had no effect on the inhibitory effect of propionate. Moreover, although the dl-isomer (10 and 20 mM) significantly reversed the inhibitory effect of propionate as compared with the d-isomer, its effect was significantly weaker as compared with the effect of LC-80. The substrate specificity of rat liver mitochondrial carnitine acetyltransferase (CAT) was more potent with propionyl CoA than with acetyl CoA. Kinetic studies indicate that the d-isomer is a competitive inhibitor of CAT. These results suggest that LC-80 is useful in the clinical treatment of organic acidemias, whereas the d-isomer has a harmful effect in clinical application.View full abstractDownload PDF (7692K)
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