Effects of Various Drugs on Myocardial Cyclic Amp
MASAHIKO SUGIURA
pg(s) 1 - 12
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Effects of norepinephrine, β3-adrenergic blocking agents, theophylline ethylenediamine (TEDA)
and digoxin on myocardial cyclic AMP concentration and those of various vasodilators both
on myocardial cyclic AMP in vivo and phosphodiesterase (PDE) activity in vitro were investigated
by radioimmunoassay of cyclic AMP.
The mean concentration of myocardial cyclic AMP was 0.318 p mole/mg in the left ventricle,
0.204 p mole/mg in the right ventricle, 0.131 p mole/mg in the left atrium and 0.094 p mole/mg
in the right atrium. Norepinephrine increased the concentration of cyclic AMP in the left
ventricle significantly, while digoxin increased it only slightly, β-adrenergic blocking agents did
not decrease it, and TEDA elevated the concentration of left ventricular cyclic AMP. The
myocardial cyclic AMP concentration of the ventricular fibrillation group increased significantly
as compared with the non-ventricular fibrillation group. Dipyridamole, TEDA and prenylamine
were determined as competitive inhibitors of purified heart PDE in vitro.
These findings suggest that norepinephrine, TEDA and propranolol affect myocardial
contractility through the cyclic AMP-PDE system and that TEDA, dipyridamole and prenylamine
cause increase of myocardial cyclic AMP through the inhibition of PDE. It also suggests that
there is a relationship between high myocardial concentration of cyclic AMP and ventricular
fibrillation induced by PDE.
Potential Deflections at the Terminal of the Frog
Muscle Spindle During Stretch
FUMIO ITO and NAGAO YOKOYAMA
pg(s) 13 - 23
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Dc-deflections were recorded with the paraffin gap method from the terminal of isolated
single.type spindles in the frog sartorius muscle during ramp-and-hold stimulation. The amplitude
of the dc-deflection over 60μV was independent of the rate of afferent discharge and was
little changed after inactivation of the axon terminal by irradiation with an ultraviolet light.
The amplitude and the polarity of the dc-deflection could be altered with currents passing
across the gap. A change in the longitudinal resistance of the axon in association with its lateral
movement during stretch of the spindle may evoke a part of the dc-deflection by dividing a
steady potential, although the dc-def1ection below 60μV in amplitude may be a genuine generator
potential.
Disaccharidase Activities in Small Intestinal
Mucosa of Alloxan-Diabetic Mice
TAKASHI HATTORI
pg(s) 25 - 35
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Increased activities of maltase and sucrase of small intestinal mucosa were found in alloxandiabetic mice.
Adrenalectomy did not affect the activities of the enzymes in normal mice, but lowered
those of alloxan-diabetic mice as well as blood sugar level. Administration of glucocorticoid
raised the enzyme activities in normal mice, non-diabetic adrenalectomized mice and adrenalectomized al1oxan-diabetic mice.
Positive correlation was noted between blood sugar level and the activities of both enzymes.
Lactase activity did not undergo any change under these conditions.
Adrenal hyperfunction seems to play an important role in the increase of these enzyme
activities. Significance of these findings in alloxan-diabetes was also discussed.
Studies on the Additional Peptide of Procollagen
Extracted from Chick Embryo Cartilage
ATSUHIKO KUSAKABE
pg(s) 37 - 46
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The additional peptide of procollagen is thought to play an important role in its synthesis,
and attempts were made to elucidate the chemical properties of the additional peptide, particularly
in regard to the possible existence of sugar substituents.
Labeled procollagens were obtained with 4 M guanidine.HCl from chick embryo epiphyseal
cartilages which had been incubated with [14C] proline, [14C] tryptophan or [14C] glucose.
Each of the procollagen samples was digested with bacterial collagenase, and then chromatographed
on 0.1% SDS.Sephadex G-150. The [14C] glucose-labeled sample yielded a fraction with the
size of additional peptide (molecular weight, 13,200), plus collagenase-digestible small peptides.
The peptide was distinct from the collagenase.sensitive region (α-region) in having [14C]
tryptophan. On acid hydrolysis of the additional peptide samples, radioactive glucose, galactose,
mannose and a small amount of glucosamine were recovered on paper chromatography and
paper electrophoresis. Mannose and glucosamine are the components not found in the authentic
α-chain of type II collagen.
The results demonstrate that the additional peptide of cartilage procollagen is different from
the α1(II) chain in amino acid composition and also in the type of sugars attached.
Relation of the Size of Functional Hepatic
Cell Mass to the Clearance of
Indocyanine Green
HIROHIKO KOJIMA
pg(s) 47 - 55
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The correlation between fractional clearance (K) of indocyanine green (ICG) and size of
hepatic cell mass altered by functional hepatectomy as well as the degree of hepatic damage
induced by carbon tetrachloride (CCl4) was investigated in the dog. Less than 20% functional
hepatectomy produced only a minimal decrease in K of ICG probably due to the potential functional reserve of the liver, while in dogs with more than 70% functional hepatectomy, K of ICG
was remarkably decreased. K of ICG was correlated highly with the magnitude of functional
hepatectomy, i.e. the size of remaining functional hepatic cell mass. Large doses of CCl4
induced
remarkable decreases in K of ICG, being correlated positively with the degree of hepatic cell
necrosis, and CCl4 in smaller doses rather activated the hepatic cell function as reflected by higher
K values. It was concluded that K of ICG was a reliable indicator of function of hepatic cell
mass in acute or subacute damage of the hepatic cell.
The Distribution of Haptoglobin Types
in Aichi Prefecture
HIDEKI HATTORI, MINORU ASANO, MASAKAZU OYA, OSAMU SUZUKI, YOSHINAO KATSUMATA and SHOICHI YADA
pg(s) 57 - 58
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Polymorphism of haptoglobin (Hp) types was examined among 2,087 unrelated residents of
Aichi Prefecture. The phenotypic distribution obtained agreed well with the genetic hypothesis.
The frequency of Hp1 gene in Aichi Prefecture was estimated to be 0.247, which is quite similar
to those observed in other districts of Japan.
The Distribution of Red Cell Acid Phosphatase
Types in Aichi Prefecture
HIDEKI HATTORI, MINORU ASANO, MASAKAZU OYA, YOSHINAO KATSUMATA, OSAMU SUZUKI and SHOICHI YADA
pg(s) 59 - 60
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Polymorphism of red cell acid phosphatase types was examined among 573 unrelated
residents of Aichi Prefecture. The phenotypic distribution obtained agreed well with the genetic
hypothesis. No phenotypes associated with the allele Pc were detected. The frequency of Pa
gene in Aichi Prefecture was estimated to be 0.209, which is very similar to those observed
in other districts of Japan.