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Biomedical subjects

E Kato

Publications and source records attributed to E Kato.

At least 109 records · Page 6Linked to original sources
PubMed1981

Effect of aging on single nephron renin content in rats.

To investigate the relation between renin content in each juxtaglomerular apparatus and reduction of plasma renin activity (PRA) with aging, the PRA and microdissected superficial or juxtamedullary single nephron renin content (SNRC) were determined in 5 young (3-6 months) and 5 aged (13-18 months) rats fed on a normal salt diet. The mean value of the PRA in the aged group was significantly lower than that of the young group. A highly significant correlation was found between the RPA and mean values of the superficial SNRC. The mean values of both the superficial and deep SNRC in the aged rats were significantly lower than those of the corresponding zones in the young rats. It is suggested that decreased synthesis of renin in each juxtaglomerular apparatus is an important factor in the decreased PRA observed with aging.

Aging↗
PubMed1981

Effect of angiotensin I converting enzyme inhibitor, SQ 14225, on renin production and release.

Renin production and release induced by angiotensin I converting enzyme inhibitor (CEI), SQ 14225, were studied in male Wistar rats. Acute studies on the effects of CEI (4.6 mumol/kg, i.m. every 6 h for 48 H) in rats revealed a significant reduction in angiotensin II levels and a marked increase in plasma renin activity (PRA). There were no appreciable changes in renal content (RRC) and the juxtaglomerular cell granulation index (JGI). In rats which had received CEI in their drinking water (0.92 mumol/ml) for 12 days, angiotensin II levels were decreased markedly and urinary excretion of sodium was increased, but the reduction in blood pressure was slight. PRA, JGI and RRC were markedly increased in these animals. The kidneys of CEI-treated rats exhibited conspicuous vascular dilatation. CEI treatment of sodium-depleted rats resulted in a reduction of the increased JGI and RRC and in a further increase in PRA. Our findings suggest that CEI administration may initially effect stimulation of renin release from the juxtaglomerular apparatus and that prolonged CEI administration results in a gradual stimulation of renin production.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1980

Calcium localization in the sympathetic ganglion of the bullfrog and effects of caffeine.

The localization of Ca2+ in the bullfrog sympathetic ganglion was studied using electron microscopy with Oschman and Wall's technique. When the ganglion was incubated and processed in an extremely high Ca2+ solution (20 mM) for electron microscopy, electron-dense deposits (EDD) were found at or in the plasma membranes, subsurface cisterns and mitochondria of the postganglionic neurons. These EDD were proved to contain calcium by X-ray microprobe analysis. On the other hand, they were not significant in the preganglionic terminals except those in the synaptic vesicles. Addition of caffeine (10 mM) to the incubation media and fixatives caused a drastic decrease in number of EDD of the subsynaptic membranes and the subsurface cisterns. Caffeine also reduced, but less markedly, the size and number of EDD in mitochondria. Caffeine (10 mM) prolonged the afterhyperpolarization of an action potential, reduced the amplitude of the ACh (nicotinic) potential and induced slow rhythmic hyperpolarizations in a 20 mM Ca2+ solution. These effects of caffeine which were presumably the result of an increase in the intracellular free Ca2+ were discussed in relation to the morphological data.

Acetylcholine↗
PubMed1980

Renin and aldosterone in hypothyroidism: relation to excretion of sodium and potassium.

Changes in plasma renin activity (PRA) and plasma aldosterone (PA) were studied together with the urinary excretion of sodium and potassium in patients with hypothyroidism. The basal levels of PRA and PA were significantly less than those in normal subjects. However, there was no significant relationship between PRA and PA. The response of PRA after administration of 40 mg of frusemide in patients with hypothyroidism was significantly less than that in normal subjects, although the excretion of sodium was slightly higher than that in normal subjects. On the other hand, the excretion of potassium in patients with hypothyroidism was significantly lower than that in normal subjects. The responses of PA to various stimulations, such as ACTH, angiotensin II, potassium and frusemide, were equally suppressed. These results suggest that PRA and PA may be suppressed independently in hypothyroidism ,probably due to dysfunction of juxtaglomerular cells and glomerulosa cells, respectively, and the possibility that suppression of PRA and PA in patients with hypothyroidism is related to exaggerated sodium excretion and a decrease in potassium excretion cannot be ruled out.

Adult↗
PubMed1980

Inhibition of transmitter release in bullfrog sympathetic ganglia induced by gamma-aminobutyric acid.

1. Effects of gamma-aminobutyric acid (GABA) on the nicotinic synapses in bullfrog sympathetic ganglia were studied. 2. When GABA (100 microM--1 mM) was applied to the ganglion, the post-synaptic membrane depolarized slightly and transiently with a slight decrease in the membrane resistance. 3. GABA (5 microM--1 mM) decreased the amplitude of the fast excitatory post-synaptic potentials (fast e.p.s.p.) and its quantal content without a significant change in the quantal size, and these effects were seen even after the subsidence of the membrane depolarization. Picrotoxin (10 microM) did not antagonize the GABA action. 4. The sensitivity of the subsynaptic membrane to ACh was unaffected by GABA. On the other hand, the synaptic current underlying the fast e.p.s.p. was significantly depressed in the presence of GABA. 5. Neither the frequency nor the amplitude of the miniature e.p.s.p.s which occurred spontaneously were altered by GABA, in either normal or high K+ solutions. 6. The depressant action of GABA on the fast e.p.s.p. was not changed in a high K+ solution, while it was markedly decreased in a Cl- -deficient solution. 7. A small, but significant reduction in the amplitude of the presynaptic terminal spike recorded with a focal extracellular electrode was observed under the effect of GABA. 8. It was concluded that GABA inhibits synaptic transmission of bullfrog sympathetic ganglion mainly by decreasing the evoked release of transmitter and only partly by post-synpatic action. Possible mechanisms of the presynaptic action of GABA were discussed.

Acetylcholine↗
PubMed1980

The diuretic effect of piretanide in man.

The effects of 4-phenoxy-3-(1-pyrrolidinyl)-5-sulfamoylbenzoic acid (piretanide), a new loop diuretic, were investigated in five male subjects under the conditions of water load and water restriction. The results of investigations of various parameters indicate that the mode of action of piretanide is similar to that of furosemide. In particular, THC2O and CH2O were markedly reduced after the administration of piretanide, indicating that piretanide acts principally on the ascending portion of the loop of Henle and the distal tubules.

Adult↗
PubMed1979

Lysosomal acid hydrolases in lymphocytes of I-cell disease.

Several lysosomal acid hydrolases were assayed in peripheral blood leukocytes from a patient with I-cell disease by the method of Hindman, J. and Cotlier, E. ((1972) Clin. Chem. 18, 971--975). The activities of lysosomal hydrolases in polymorphonuclear cells showed no significant differences between the patient, the parents, and normal controls, while lymphocytes from the patient exhibited the reduced activities of alpha- and beta-galactosidases, beta-glucuronidase, and N-acetyl-beta-glucosaminidase. After phytohemagglutinin-stimulated culture, lymphocytes from the patient showed a more definite reduction in the activities of these lysosomal enzymes; the activities of beta-glucuronidase, alpha-mannosidase, and N-acetyl-beta-glucosaminidase were reduced to about 20--30% of the activity in the phytohemagglutinin-stimulated control cultures, and the activities of alpha- and beta-galactosidases to 10% or less. Lymphocytes from the parents showed no significant difference in the activities of these enzymes from the controls, whether stimulated or not.

Adolescent↗