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Biomedical subjects

M Asano

Publications and source records attributed to M Asano.

At least 595 records · Page 33Linked to original sources
PubMed1976

Zonation of the adrenal cortex. I. Isolation of mitochondria from the zona glomerulosa of the bovine adrenal cortex.

Isolation procedures for mitochondria from the zona glomerulosa of the bovine adrenal cortex are described in comparison to those isolated from the zona fasciculo-reticularis. The cristal membranes of mitochondria in the zona glomerulosa in situ are tubular or tubulo-vesicular, whereas those of mitochondria in the zona fasciculo-reticularis in situ are vesicular. When mitochondria are isolated from the former zone, they invariably showed a condensed configuration regardless of isolation media, whereas those isolated from the later zone in a ST medium showed an orthodox configuration. When Ca2+ was added to mitochondria isolated form either zone in an STE medium in the condensed configuration, transition from the condensed to the orthodox configuration took place; the cristel membrane of mitochondria from the zona glomerulosa became tubular or tubulo-vesicular and those of mitochondria from the zona fasciculo-reticularis became vesicular. Purity of mitochondria thus obtained from the zona glomerulosa was examined by electron microscope and marker enzymes. Coupling efficiency of mitochondria was found to be remarkably affected by temperature during the isolation procedures and a choice of substrates.

Adrenal Cortex↗
PubMed1976

Relaxation of isolated rabbit arteries by fusaric (5-butylpicolinic) acid.

The influence of fusaric (5-butylpicolinic) acid on vascular contractile or relaxing response was examined in different isolated arterial preparations of the rabbit. Prior exposure (10 minutes) to 1 x 10(-4) to 1 x 10(-3) M fusaric acid decreased contractile responses elicited with norepinephrine, histamine, serotonin, acetylcholine, angiotensin II and KCl in helical strips of rabbit aorta and superior mesenteric, carotid, renal, and femoral arteries. Fusaric acid produced a shift to the right and down in the dose-response curves to all tested agonists, and antagonized acetylcholine and serotonin most effectively among these agonists. These results indicate that fusaric acid antagonized nonspecifically these contractile agonists. When blood vessels were contracted with prostaglandin F2alpha, fusaric acid caused relaxation of rabbit aorta and superior mesenteric, carotid, renal, and femoral arteries in a dose-dependent fashion. Among blood vessels tested superior mesenteric arteries were relaxed the most effectively by fusaric acid. The concentration of fusaric acid which induced 50% relaxation of aortic strips was about 10-fold higher than that of papaverine. Propranolol and atropine did not affect fusaric acid-induced relaxation, suggesting that fusaric acid did not work through beta adrenergic or cholinergic receptors. Ethylene glycol bis(beta-aminoethyl-ether)-N,N'-tetraacetic acid which chelates with Ca++ caused blood vessel relaxation in doses similar to those of fusaric acid. As fusaric acid is known to chelate Ca++, a possible mechanism of fusaric acid to relax blood vessel through Ca++ depletion is discussed briefly.

Aminophylline↗
PubMed1975

Mechanism of the formation of megamitochondria induced by copper-chelating agents. I. On the formation process of megamitochondria in cuprizone-treated mouse liver.

Processes of the formation of cuprizone-induced megamitochondria in mouse liver have been studied in detail by electron microscopy. The earliest change observed was the presence of large intramitochondrial granules. The next stage was the formation of myelin figures by which mitochondria were apparently connected. The third stage was characterized by megamitochondria connected with each other by their outer membranes. Continuity of mitochondria were further examined by serial sections, and megamitochondria were proved to be connected to each other far more frequentlythan expected on one plane of section. A model for the mechanism of megamitochondrial formation is proposed based on electron microscopic evidences, involving the fusion of mitochondrial membranes. Possibility is also discussed that cuprizone-induced megamitochondria may fuse to one single branching mitochondrion.

Adrenal Glands↗
PubMed1975

Mechanism of the formation of megamitochondria induced by copper-chelating agents. III. Formation and some biochemical properties of megamitochondria induced by diethyldithiocarbamate (DDC).

Sodium diethyldithiocarbamate (DDC), a copper-chelating agent, has induced megamitochondria in mouse hepatocytes simply by feeding the animal with a diet containing the noxious agent. Megamitochondria have been isolated from the liver, specified above, in a medium containing albumin. Phosphorylating capacities of such megamitochondria have revealed that they are tightly coupled. Biochemical properties of megamitochondria, such as cytochrome contents, activities of copper-containing enzymes. and contents of Cu2+, strongly suggest that copper-chelating action of the agent may not be related to the formation of megamitochondria just as in the case of cuprizone-induced megamitochondria. Moreover, contents of divalent metals such as Ca2+ and Mg2+ were drastically decreased in the mitochondrial preparation specified above. Similarities in biochemical aspects of DDC-induced megamitochondria to those of cuprizone-induced megamitochondria together with ultrastructural changes in the liver and clinical appearances of the mouse treated with the agent would strongly suggest that the mechanism of the formation of megamitochondria induced either by DDC or by cuprizone may be the same.

Animals↗
PubMed1975

Mechanism of the formation of megamitochondria induced by copper-chelating agents. II. Isolation and some properties of megamitochondria from the cuprizone-treated mouse liver.

Megamitochondria have been isolated from the liver of the cuprizone-fed mouse with the aid of bovine serum albumin. Phosphorylating capacities of megamitochondria, specified above, in terms of respiratory control ratios and ADP/O ratios have revealed that they are not uncoupled completely. Biochemical properties of megamitochondria which are related to the metabolism of copper have shown that copper-chelating action of cuprizone may not be directly related to the formation of megamitochondria in vivo. Namely, cytochrome contents, activities of cytochrome oxidase and monoamine oxidase and contents of copper of megamitochondria were unchanged compared with those of the control. However, contents of divalent metals such as Ca-++ and Mg-++, especially that of the former, in megamitochondria decreased significantly. It is suggested that cuprizone may alter Mg-++/Ca-++ ratios when it is administered in vivo, and that changes in the ratio might play a key role in the formation of megamitochondria.

Animals↗