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Biomedical subjects

T Komuro

Publications and source records attributed to T Komuro.

At least 127 records · Page 7Linked to original sources
PubMed1980

The localization of acetylcholinesterase in the optic lobe in the developing chick embryo.

The localization of acetylcholinesterase (AChE) in the optic lobe in the developing chick embryo was studied histochemically and biochemically. The histochemical reaction of AChE increased remarkably between stage 42 and 44 especially in the neuropile. The increase of the biochemical activity of the AChE in the synaptic membrane fraction occurred at a later stage than that in the microsomal fraction. These findings can be interpreted as the result of axonal transport of the enzyme from the synthetic to the synaptic site.

Acetylcholinesterase↗
PubMed1980

The fine structure of smooth muscle cells and their relationship to connective tissue in the rabbit portal vein.

The smooth muscle of rabbit portal vein was studied by electron microscopy with particular emphasis on the mechanical linkage between the muscle cells and on the distribution of connective tissue. The media of this vein is composed of inner circular and outer longitudinal muscle layers which are orientated almost perpendicularly to each other. The muscle of the inner circular layer shows very irregular contours with much branching and anastomosing of the cytoplasmic processes, which often make membrane contacts with neighbouring cells to form an extensive network of cytoplasmic processes. The muscle cells of the outer longitudinal layer are arranged in densely packed bundles and are spindle-shaped, with no branching processes. Opposing dense areas from neighbouring cells, with variable gap distances (30--100 nm) and close membrane contacts (intermediate junctions) with a gap of 11 nm were observed in both circular and longitudinal muscle layers. In the terminal regions of muscle cells in both circular and longitudinal layers a specialized anchoring structure was present which was closely related to extracellular elastic tissue. Muscle cells in the longitudinal layer showed the most elaborate structure, the tapering end of the muscle cell showing a honeycomb-like structure penetrated by columns of connective tissue compounds. The functional implications of these structures are discussed.

Animals↗
PubMed1980

Renal function, plasma renin, and spontaneous diuresis in an advanced stage of hypertension in rats.

Relationship of renal function and plasma renin level to a spontaneous diuresis in an advanced stage of hypertension was examined in the stroke-prone spontaneously hypertensive rats (SHRSP). For a comparison, it was also investigated in 2 kidney 1 clip (1CR) and 2 kidney 2 clip (2CR) models of renovascular hypertensive rats. The spontaneous diuresis was usually associated with an elevation of plasma renin level and an impairment of renal function in SHRSP and 1CR. In SHRSP, renal plasma flow showed an inverse correlation to the plasma renin level. The diuresis, however, is not prerequisite to the increase in plasma renin or to the renal impairment, since the latter changes were not always accompanied by diuresis. No correlations were found between these factors in 2CR. Remittent diuresis was observed in many 2CRs and 2 SHRSPs with normal renal function, indicating that renal damage underlies the continuous progression of the diuresis observed in most cases of SHRSP and 1CR. Both sodium and potassium balances tended to be negative in 1CR and 2CR in the diuretic phase, whereas potassium alone showed this tendency in SHRSP. The negative balances, if any, were not due to an excessive loss of the electrolytes but attributed mainly to a decrease in intake. The critical level of blood pressure for the spontaneous diuresis was highest in SHRSP and lowest in 1CR. It is probable that an interaction and cooperation between high blood pressure, impaired renal function and high plasma renin participate in the mechanism of the spontaneous diuresis during the development of malignant phase of hypertension of the rat.

Aldosterone↗
PubMed1979

Pathophysiological studies on hypertension induced in rats by kidney extract and salt.

The renin-angiotensin-aldosterone system, electrolyte and water balance, body fluid, and neurogenic tone and reactivity of the vasculature were studied in hypertension induced in uninephrectomized rats by repeated injection of renin-rich kidney extract and 1% saline drinking. The control rats were injected with physiological saline. Various measurements were made in conscious rats on the 10th day of the treatment. As compared with the control, plasma renin concentration and serum sodium increased significantly, while plasma aldosterone and renal excretory function did not differ. Blood volume (BV) expressed as per body weight increased significantly, but absolute BV, absolute or body weight-related plasma volume and hematocrit were not significantly different. The hypotensive effect of 1-Sar-8-Ile-angiotensin II was negligible 12 hours after the preceding injection of kidney extract. It was small but significant 1 hour after the injection. Increase in water turn-over and fractional sodium excretion occurred during the development of hypertension. Spironolactone did not significantly modify the developmental course. We observed increased depressor response to hexamethonium and increased reactivities to noradrenaline and angiotensin II (A II); these response curves relatively resembled those of spontaneously hypertensive rats. Hypertensive vascular changes were seen in the kidney and heart by histology. Thus, it was suggested that a direct vascular action of A II played a partial role in this hypertensive process while aldosterone played little role. The significance of BV increase and possible contribution of A II's other actions were discussed.

1-Sarcosine-8-Isoleucine Angiotensin II↗
PubMed1976

High-speed liquid chromatographic determination of antiepileptic drugs in human plasma.

A high-speed liquid chromatographic method for the simultaneous determinations of diphenylhydantoin, phenobarbital and carbamazepine in human blood plasma is presented. This method involves two step extraction procedures with chloroform and uses 2 X 50 cm long stainless steel columns packed with a anion exchange resin, with a mobile phase of 4 mM ammonium phosphate buffer solution, pH 6.2 at a flow rate of 0.40 ml/min. The results presented show linear calibration curves and quantitative determinations as low as 1.0 mug of each drug added to 0.5 ml plasma. This method has a sensitivity sufficient to detect human plasma levels after therapeutic clinical doses.

Carbamazepine↗
PubMed1976

Plasma renin and vascular complications in substrains of the spontaneously hypertensive rat, with a reference to water and electrolyte balance.

The stroke-prone and stroke-resistant substrains of the spontaneously hypertensive rat (SHR) were employed for an evaluation of possible role of reninangiotensin system and of water and electrolyte balances in inducing hypertensive vascular lesions. Serial study on plasma renin level and vascular changes did not support the hypothesis that plasma renin is a major risk factor in the development of cardiovascular complications. The high plasma renin level seen in advanced stages of hypertension appeared to be a result of severe vascular damages, indicating malignant transformation of hypertension. In this state, water turnover was enhanced without any abnormality in electrolyte balances. A possible mechanism involved in the malignant course of hypertension is discussed.

Animals↗
PubMed1975

The renal chloride cell of the fresh-water catfish, Parasilurus asotus, with special reference to the tubular membrane system.

The kidney of the fresh-water catfish, Parasilurus asotus, was examined by electron microscopy. A special type of cell, very similar in appearance to the chloride cell of the teleostean gill filaments, is found in the kidney and is referred to as a renal chloride cell. This cell is characterized by an extensive tubular membrane system with a rather constant diameter of approximately 600 A. A number of mitochondria are closely associated with this system. Application of ruthenium red as an extra-cellular space marker revealed that the tubular system is a highly organized derivative of the cell membrane, infolded from the basal and lateral surfaces of the cell. The fine structural resemblance to other types of cells known to possess active transport of electrolytes suggests that these cells are involved in intrarenal osmoregulation.

Animals↗