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Biomedical subjects

S Kikuchi

Publications and source records attributed to S Kikuchi.

At least 541 records · Page 30Linked to original sources
PubMed1978

Antidiuresis induced by beta1- and beta2-adrenergic agonists in ethanol-anesthetized rats.

The beta1- and beta2-components in antidiuresis and sodium retention induced by beta-adrenergic agonists were analysed in ethanol-anesthetized, water-diuretic rats. Intravenous infusions of isoprenaline, salbutamol and carbuterol did not affect insulin clearance but increased plasma renin concentration to the same same extent. Propranolol completely blocked the decreases in urine volume (V) and urinary sodium excretion (UNaV) induced by isoprenaline; practolol (beta1-blocker) inhibited only the decrease in UNaV and butaxamine (beta2-blocker) inhibited only the decrease in V. The ratios of doses of beta-agonists which decreased UNaV and by 50% (ED50 UNaV decrease/ED50 V decrease) were 0.34, 0.68, 1.56 and 2.36 for isoprenaline, tretoquinol, salbutamol and carbuterol, respectively. This increasing order of the ratios coincided with the order reported for the preponderance of the beta2- over beta1-component of these agonists. These results indicate that the decrease in UNaV induced by beta-agonists is related to beta1 stimulation, while the decrease in V is related to beta2 stimulation.

Adrenergic beta-Agonists↗
PubMed1978

A D-serine dehydratase acting also on L-serine from Klebsiella pneumoniae.

D-Serine dehydratase [EC 4.2.1.14] was purified from a strain of Klebsiella pneumoniae 140-fold from crude extract with a yield of 5%. This enzyme catalyzed formation of pyruvate and ammonia not only from D-serine but also from L-serine, and also catalyzed the formation of alpha-ketobutyrate and ammonia from D-threonine. Km values for D-serine, L-serine, and D-threonine were 2.8 mM, 20 mM, and 3.6 mM, respectively. Km for pyridoxal 5'-phosphate was 2.5 micron. The molecular weight was estimated to be 46,000 by Sephadex G-150 gel filtration and 40,000 by SDS-polyacrylamide gel electrophoresis. This enzyme was inducible by D-serine. Induction by casamino acids appeared to depend on the presence of D-serine.

Enzyme Induction↗
PubMed1978

Effect of the diuretic, 1,4-dimorpholino-7-phenylpyrido[3,4-d]-pyridazine (DS-511) and its derivatives on ADH-cyclic AMP system in rat renal medullary slices.

The effect of the diuretics, 1,4-dimorpholino-7-phenylpyrido[3,4-d]pyridazine (DS-511) and its 4'-hydroxy derivative [DS-511(4'-OH)] on the ADH-cyclic AMP system was studied in slices of rat renal medulla. These compounds alone did not affect the basal level of cyclic AMP in the slices. Preincubation with 10(-6) mol DS-511 or 10(-7) to 10(-5) mol DS-511-(4'-OH) in the presence of theophylline, inhibited arginine vasopressin stimulated formation of cyclic AMP, but after washing the slices the formation was restored. Etacrynic acid required higher concentrations such as 10(-5) and 10(4-) mol to cause inhibition. No effect was observed with furosemide and hydrochlorothiazide in concentrations up to 10(-4) mol. DS-511(4'-OH) at concentrations higher than 10(-6) mol inhibited the activity of cyclic AMP-phosphodiesterase in the medullary homogenate. These results suggest the water diuretic action of DS-511 is partly mediated by its inhibition of the ADH-cyclic AMP system.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1978

Inhibitory effect of 1,4-dimorpholino-7-phenylpyrido[3,4-d]-pyridazine (DS-511) and its 4'-hydroxy derivative on antidiuretic action of vasopressin in rats.

The water-diuretic features of 1,4-dimorpholino-7-phenylpyridol[3,4-d]-pyridazine (DS-511) and its water-soluble 4'-OH derivative [DS-511(4'-OH)] were investigated. In saline-infused rats the minimum i.v. diuretic dose of DS-511(4'-OH) was 1.0 micrograms/kg/min, while in water-diuretic rats the minimum dose was 50 micrograms/kg/min. Intravenous infusion of DS-511 or DS-511(4'-OH) at rates of 1 to 10 micrograms/kg/min caused a dose-dependent inhibition of the ADH-induced antidiuresis in water-diuretic rats, and a decrease in urinary osmolality. However, hydrochlorothiazide even at 500 micrograms/kg/min did not alter the antidiuresis, but increased the osmolality. Furosemide at a rate of 10 micrograms/kg/min increased urinary excretion of water and sodium in both saline-infused and water-diuretic rats, but the same dose did not inhibit the ADH-induced antidiuresis. These findings indicate that the specific anti-ADH action at relatively low doses of DS-511 and DS-511(4'-OH) is partly involved in the diuretic mechanism of these agents.

Animals↗
PubMed1978

1,4-Dimorpholino-7-phenylpyrido[3,4-d]pyridazine (SD-511) as a new type of diuretic agent.

Diuretic features of 1,4-dimorpholino-7-phenylpyrido[3,4-d]pyridazine (DS-511) were studied in rats and mice. DS-511 was similar in diuretic effect to that of hydrochlorothiazide (HC) in both species, but was more water diuretic and less potassium-releasing than HC. After oral administration of DS-511 to rats the diuretic effect promptly appeared and lasted for 4 to 5 h. These patterns on onset and duration were similar to those of furosemide and acetazolamide (AZ). DS-511 was effective in experimentally induced acidotic and alkalotic rats. When DS-511 was used in combinations with other diuretics such as HC, AZ and triamterene at their maximum effective doses, urine volume and sodium excretion further increased, but potassium did not. Diuretic activity of DS-511 was not reduced by daily oral administration for 10 days to rats. In rats DS-511 reversed antidiuretic hormone (ADH)-induced antidiuresis. These findings suggest that DS-511 differs in mode and/or site of action from the known diuretics.

Acidosis↗
PubMed1977

Mitochondria-rich (chloride) cells in the gill epithelia from four species of stenohaline fresh water teleosts.

The mitochondria-rich (chloride) cells have been found to be present in the gill epithelia of four species of stenohaline fresh water teleosts. The cytoplasm of these chloride cells contains an extensive network of cytoplasmic tubules which communicate with intercellular spaces bordering the lateral and basal cell surfaces. Numerous vesicles with fairly electron-dense interiors are also present in the apical cytoplasm of chloride cells. The apical surface of a chloride cell forms an apical pit, but the lumen of the pit does not appear to be in continuity with the interior of the apical vesicles and tubules inside the cell. When Carassius auratus were kept in 100, 200, 300, and 400 mOsm-diluted sea water for a month, no appreciable changes occurred in the number and fine structure of the chloride cells, except for a dilation of the apical vesicles and a slight decrease in diameter of the cytoplasmic tubules in these cells in the fishes kept in 300 and 400 mOsm. These results suggest that chloride cells may be a rather common occurrence in the gill epithelia of stenohaline fresh water teleosts, and may function in ion transport in these fishes in fresh water environments.

Animals↗