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Biomedical subjects

K Hiwada

Publications and source records attributed to K Hiwada.

At least 379 records · Page 21Linked to original sources
PubMed1980

Effects of prostaglandins on renin substrate production by the liver.

1. The effects of prostaglandin (PG) E1, PGE2 and PGF2 alpha on plasma renin substrate concentration in rats and renin substrate production by perfused rat liver were investigated. 2. After bilateral nephrectomy, both plasma renin substrate concentration and renin substrate production were remarkably elevated. 3. The increase in plasma renin substrate level and production of renin substrate by the liver after nephrectomy was markedly suppressed by the treatment with PGE1 or PGE2. 4. In contrast PGF2 alpha had no suppressive effect on renin substrate synthesis. 5. These findings suggest that PGE1 and PGE2 might be inhibitory factors in the regulation of renin substrate synthesis.

Angiotensinogen↗
PubMed1980

Isolation and characterization of membrane-bound arylamidases from human placenta and kidney.

Membrane-bound arylamidases (EC 3.4.11.2) from human placenta and kidney were purified. The enzymes were solubilized from membrane fractions using trypsin. Purification procedures included DEAE-cellulose column chromatography, concanavalin-A--Sepharose 4B column chromatography, hydroxyapatite column chromatography and Sephadex G-200 gel filtration. The final recoveries of placental and kidney enzymes were 22.0% and 20.8% respectively. Polyacrylamide gel electrophoresis, analytical isoelectric focusing, immunoelectrophoresis and ultracentrifugation indicated the homogeneity of both purified enzymes. Equilibrium ultracentrifugation showed molecular weights of 193000 for placental enzyme and 211000 for kidney enzyme. Electrophoresis of the enzymes under denaturing conditions on dodecylsulfate/polyacrylamide gel indicated that each enzyme was a dimer consisting of two identical subunits. Isoelectric points of placental and kidney enzymes were 4.20 and 4.32 at 4 degrees C, respectively. The amino acid compositions of the two membrane-bound arylamidases were similar. The carbohydrate accounted for 18.2% of placental enzyme and 17.4% of kidney enzyme. The purified placental enzyme had a specific activity of 60.1 mumol min-1 (mg protein)-1 and the kidney enzyme had a specific activity of 96.4 mumol min-1 (mg protein)-1. Kcat values of placental and kidney enzymes were 187.8 s-1 and 328.6 s-1, respectively. The hydrolytic coefficient (Kcat/Km) of placental enzyme for L-alanyl-beta-naphthylamide was 2159 mM-1 s-1 and that of kidney enzyme was 3778 mM-1 s-1. Rabbit antibodies against placental and kidney membrane-bound arylamidases inhibited the activities of the corresponding antigens, but the inhibitions were never complete. Three membrane-bound arylamidases from placenta, kidney and renal cell carcinoma were immunochemically indistinguishable.

Amino Acids↗
PubMed1980

Isolation and characterization of human renin substrate.

Human renin substrate (angiotensinogen) was purified from outdated bank plasma. Purification procedures included ammonium sulfate precipitation, DEAE-cellulose column chromatography, concanavalin A-Sepharose column chromatography, Hydroxylapatite column chromatography preparative isoelectric focusing and Ultrogel AcA 44 gel filtration. The final recovery was 10% and the specific angiotensin I content of 10.5 micrograms/mg of protein was obtained. Polyacrylamide gel and SDS-polyacrylamide gel electrophoresis and analytical ultracentrifugal analyses showed the homogeneity of the purified renin substrate. The molecular weight of 60900 was determined by sedimentation equilibrium studies. Human renin substrate was a glycoprotein containing 13% carbohydrate. Cystine could not be detected on amino acid analysis. The purified renin substrate showed the isoelectric point heterogeneity (pI, 4.6 and 4.9).

Amino Acid Sequence↗
PubMed1980

Pathophysiological characteristics of labile hypertensive patients determined by the cold pressor test.

Hemodynamic changes during the cold pressor test were examined in Type I labile (juvenile labile) hypertensive patients, Type II labile (middle aged labile) hypertensive patients, established hypertensive patients and normal subjects. In normal, Type I labile hypertensive and established hypertensive subjects, the pressor response during the test was accounted for chiefly by a rise in peripheral resistance. In Type II labile hypertensive patients, an increase in blood pressure during cold stimuli was accompanied by an augmented cardiac output. Therefore, Type II labile hypertension is separated clearly from other types of hypertension with respect to hemodynamic changes during the test. In Type II labile hypertensive patients, however, diazepam reduced an increase in cardiac output during the test, resulting in hemodynamic changes similar to those of normal subjects. After atropinization, the hemodynamic pattern of Type I and established hypertensives changed similar to that of Type II labile patients during the cold pressor test. It is concluded that an excessive cardiac output caused by the cold stimuli is a distinctive hemodynamic characteristics of Type II labile hypertensive patients, and this distinctive hemodynamic characteristics might be due to the decreased parasympathetic tone.

Adult↗
PubMed1980

Effects of insulin and glucagon on production of renin substrate by the isolated rat liver.

An isolated rat liver perfusion system was used to study the effects of insulin and glucagon on renin substrate production. Normal livers synthesized renin substrate at a rate of 28.3 +/- 3.8 (S.E.M.) ng angiotensin I equiv./g liver each h (n = 8). The addition of insulin (more than 0.1 i.u.) to the perfusion significantly enhanced the production of renin substrate which was about twofold higher than normal control values (P less than 0.001). However, glucagon (20 micrograms) did not affect the synthesis of renin substrate. These results indicated that insulin promoted the synthesis of renin substrate by the isolated rat liver.

Angiotensinogen↗
PubMed1980

Reduced responses of renin release to three different stimuli in essential hypertensive patients of stage II (WHO stage classification).

The responses of renin release to three different stimuli, such as 1) head-up tilt, 2) administration of loop diuretics(bumetanide) and 3) low sodium diet + administration of bumetanide + ambulation were examined in essential hypertensive patients and normotensive subjects. Essential hypertensive patients were classified as stage I and II according to WHO stage classification. Groups studied were age-matched. The responses of renin release to three stimuli did not significantly differ in normotensive subjects (n = 13, 42 +/- 2(SEM) years old) and essential hypertensive patients of stage I (n = 15, 44 +/- 2). However, essential hypertensive patients of stage II (n = 20, 44 +/- 1) showed significantly lower responses of renin release to all three stimuli than essential hypertensive patients of stage I and normotensive subjects. The results suggest that the suppression of renin release is related in part to the development of hypertension.

Adult↗
PubMed1979

Placental type of membrane-bound arylamidase (Shiba isoenzyme) found in human cancerous lung.

A placental type of membrane-bound arylamidase (Shiba isoenzyme) was found in the tissue of adenocarcinoma of the lung. Cancerous lung membrane-bound arylamidase had the same electrophoretic mobility, isoelectric point (pH 4.2), and susceptibility to SDS inactivation as placental membrane-bound arylamidase. Cancerous lung membrane-bound arylamidase had molecular weight and kinetic properties similar to normal lung membrane-bound arylamidase, but differed from the normal lung membrane-bound arylamidase with respect to electrophoretic mobility, isoelectric point, heat stability and inactivation by SDS.

Aminopeptidases↗
PubMed1979

No evidence for the existence of a species-specific renin substrate in plasma from normal and bilaterally nephrectomized rats.

Renin substrate in plasma from normal and biolaterally nephrectomized rats was measured using an excess of rat or rabbit renin which had the same pressor activity when directly assayed in the rat. The amounts of angiotensin I generated with an excess of rat renin were similar to those generated with an excess of rabbit renin in plasma from normal and bilaterally nephrectomized rats. Further addition of an excess of homologous renin to the incubation mixture did not generate more angiotensin I from normal and bilaterally nephrectomized rat plasma which had been incubated before with an excess of rabbit renin. The isoelectric focusing profiles of plasma renin substrate from normal and bilaterally nephrectomized rats were almost identical using an excess of either rat or rabbit renin. It is concluded that there is no species-specific renin substrate for homologous renin in normal or bilaterally nephrectomized rats.

Angiotensin I↗
PubMed1979

Measurement of plasma renin concentration using exogenous human renin substrate in normal subjects: correlation with plasma renin concentration and plasma aldosterone concentration.

Measurement of plasma renin concentration (PRC) was done in normal subjects at rest and under acute stimulation of renin release under unrestricted sodium intake. Concurrent measurements of plasma renin activity (PRA) and plasma aldosterone concentration (PA) were carried out. The mean values of PRC at rest and after stimulation of renin release were 12.8 +/- 1.3 (SEM) and 21.7 +/- 4.4 (SEM) ng AT I/ml/h, respectively. These corresponded to renin contents of 3.4 +/- 0.34 (SEM) X 10(-5) Goldblatt units and 5.8 +/- 0.36 (SEM) respectively. The mean percent increase of PRC (82.1 +/- 19.3 (SEM)) %) was almost indentical to that of PA (81.5 +/- 16.4 (SEM) %), but differed from that of PRA (269 +/- 83.1 (SEM) %). A very high correlation between concurrent PRC and PA (r = 0.92, P less than 0.001) was found in normal subjects at rest and under acute stimulation of renin release. A good correlation between PRC and PRA (r = 0.85, P less than 0.001) was also observed. However, a higher correlation between percent increases of PRC and PA (r = 0.92, P less than 0.001) than that of PRA and PA (r = 0.80, 0.01 less than P less than 0.005) was found. Results show that PRA is a good index of the renin content in plasma in normal subjects at rest and PRC reflects actual renin concentration in plasma at rest as well as under stimulation of renin release.

Adult↗
PubMed1978

Angiotensin I-converting enzyme in human urine.

It was demonstrated that angiotensin I-converting enzyme was excreted in human urine. The mean activity of the enzyme in normal urine was found to be 0.38 +/- 0.04 (S.E.M.) units/day (n = 18) and the enzymic activity correlated well with the concentration of the excreted sodium (r = 0.76, p less than 0.005). Urinary angiotensin I-converting enzyme was partially purified. Three different molecular weights of enzyme (greater than 400 000, 290 000 and 140 000) were demonstrated by Sephadex G-200 gel filtration. The enzymic properties of these three enzymes were identical with those of angiotensin I-converting enzyme from human lung with regard to inhibitory effects (bradykinin potentiator c and Arg-Pro-Pro), Cl- dependency, pH optimum and KM value.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1978

A placental type of membrane-bound arylamidase in serum and ascites from a patient with renal cell carcinoma.

A placental type of membrane-bound arylamidase was detected in serum and ascites from a patient with renal cell carcinoma by isoelectric focusing. The enzyme had the same molecular weight, electrophoretic mobility on polyacrylamide gel, isoelectric point and KM value as placental membrane-bound arylamidase. The new type of membrane-bound arylamidase was named Shiba-isoenzyme after the patient's name.

Aminopeptidases↗
PubMed1978

Membrane-bound arylamidase from human hepatoma cells having the same electrophoretic mobility as placental membrane-bound arylamidase.

A membrane-bound arylamidase from well-differentiated hepatocellular carcinoma having the same electrophoretic mobility as placental membrane-bound arylamidase was found. The enzyme was found to be a sialoprotein and was activated by Co2+. Hepatoma membrane-bound arylamidase had a similar molecular weight (240 000) and kinetic properties to normal liver membrane-bound arylamidase, but differed from the liver enzyme with respect to electrophoretic mobility, heat stability and urea inactivation.

Aminopeptidases↗