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Biomedical subjects

K Moriya

Publications and source records attributed to K Moriya.

At least 145 records · Page 8Linked to original sources
PubMed1977

Role of ketone bodies in nonshivering thermogenesis in cold-acclimated rats.

The role of ketone bodies (KB) in nonshivering thermogenesis was investigated in warm- and cold-acclimated rats with and without norepinephrine (NE) loads. NE-induced calorigenesis, as evidenced by changes in rectal temperature, was highly developed in cold-acclimated rats, but the levels of blood KB and free fatty acids (FFA) remained almost unaltered. In contrast, FFA turnover rate in cold-acclimated rats under NE load was much greater than in warm-acclimated rats. Similarly, turnover rate of beta-hydroxybutyrate estimated from decay curves of the endogenous substrate in functionally eviscerated rats was significantly higher in cold- than warm-acclimated rats. Perfused livers from cold-acclimated rats produced more KB than warm-acclimated ones. No significant effect of NE load was observed in either group. Quantitative analysis shows that the turnover rate of KB in vivo essentially equals the production rate in the perfused liver when no exogenous NE is added. In contrast, under constant NE infusion the turnover rate in vivo was almost double that of the perfused liver. These results indicate that KB are an energy source as important as FFA in nonshivering thermogenesis. It may be further surmised that increased KB production in vivo, particularly in the cold-acclimated state, is affected by factor(s) other than NE.

Acclimatization↗
PubMed1977

Effects of norepinephrine on uptake and oxidation of plasma free fatty acids in cold-acclimated rats.

In order to know the mode of action of norepinephrine in enhanced utilization of plasma free fatty acids (FFA) in cold acclimation, albumin-bound 14C-palmitate was infused intravenously at a constant rate into cold- and warm-acclimated rats under pentobarbital anesthesia with and without norepinephrine infusion. Rectal temperature, CO2 output and plasma FFA, from which the rates of FFA uptake and oxidation were calculated, were determined simultaneously. Similar fractions, that is, 7 and 5% of the total uptake of plasma FFA by the tissue were immediately oxidized in both cold- and warm-acclimated rats, respectively. Norepinephrine infusion caused a significant increase in all the parameters examined. In addition, during hormone infusion the percentage of FFA uptake oxidized was elevated from 22% in control to 50% in cold-acclimated rats. This increment was accompanied with greater increases in rectal temperature and CO2 output. Similarly, in functionally eviscerated cold-acclimated rats, norepinephrine induced a greater increase in the percentage of FFA uptake oxidized than in eviscerated controls. These results indicate that although the FFA uptake was increased simultaneously norepinephrine infusion casued a more marked acceleration of the oxidation of plasma FFA in the cold-acclimated rats than in control rats.

Acclimatization↗
PubMed1976

Hyperreactive arterial endothelial cells: a clue for the treatment of atherosclerosis.

Arterial endothelial cells, which are capable of phagocytizing carbon particles of the same size as beta- and pre-beta-lipoprotein, were found only in endothelial cells of arterial segments susceptible to atheromatous changes in susceptible animal species, and the distribution closely corresponded to the susceptibility. The distribution of such endothelial cells is dense in large arteries, in the openings to their branches, especially in downstream portions, of rabbits, hens, and cocks; however, the distribution is relatively scanty in arteries of rhesus monkeys and is very scanty in dogs. Carbon particles were also rare in the suckling rabbit and tended to increase with age. They were not found in Wistar rats but were found in spontaneously hypertensive rats, which showed a characteristically diffuse distribution, even in relatively small arteries. The carbon particles, phagocytized, were released to the subendothelial space but were difficult to pass through the internal elastic lamina and tended to stagnate there for more than one month. The authors therefore call these cells hyperreactive endothelial cells. Various vasoactive substances, such as angiotensin II, histamine, and serotonin, significantly enhanced the phagocytic activities of arotic endothelial cells in rabbits; epinephrine and norepinephrine also slightly enhanced these activities. Various smooth muscle relaxants, such as ATP, pyridinol carbamate (ATP synthesis-enhancing substance), cycli-AMP, dibutyryl cycli-AMP, phthalazinol (cyclic-AMP phosphodiesterase inhibitor), iproveratril (calcium entry-inhibiting substance), colchicine, and vinblastine, with their different modes of action, commonly inhibited phagocytic activities, a finding that suggests a significant role for contractile protein in the permeability problem of atherogenesis. The atheromatous lesions of cholesterol-fed rabbits exhibited a striking increase in hyperreactive endothelial cells, accompanied by a marked rise in the activity of low-Km cyclic-AMP phosphodiesterase activity in atheromatous lesions and adjacent muscular layers, especially in rabbits with rapidly progressing atheroma.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1975

Effects of norepinephrine and thyroxine on the turnover rate of plasma free fatty acids.

Effects of norepinephrine infusion on rectal temperature, plasma free fatty acids (FFA) concentration and its turnover rate were studied in rats treated chronically with norepinephrine, thyroxine, or both. Chronic treatments with these hormones resulted in greater increases in rectal temperature and FFA turnover rate in response to norepinephrine as compared with the alterations in controls. Norepinephrine-induced elevation of FFA concentration was smaller in norepinephrine-treated and norepinephrine plus thyroxine-treated rats than in controls, and in thyroxine-treated rats the elevation was similar to that of controls. The regression coefficient of FFA concentration of its turnover rate was greater in all the treated groups than in controls although positive correlations were observed among both variables in the former and the latter. From the results it was inferred that the greater increase in removal of plasma FFA was produced by norepinephrine in parallel with the greater increase in rectal temperature by norepinephrine in rats treated with norepinephrine or thyroxine than in the controls. The effects of norepinephrine infusion were also studied in surgically thryoidectomized rats. In thyroidectomized rats adapted to warm or cold, the smaller increases in rectal temperature and ithe turnover rate of plasma FFA were induced by norepinephrine as compared with the changes in intact rats. The alterations in FFA concentration produced by norepinephrine were less in warm-adapted thyroidectomized rats and greater in cold-acclimated thyroidectomized rats than in respective controls.

Animals↗