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Query: UMLS:C0009443 (cold)
 92,137 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In white rats both adapted and unadapted to cold, the RQ dynamics during cold exposure, noradrenaline and ganglion blocking agent administration, were studied. The adapted animals' RQ in thermoneutral conditions was shown to be a little higher than in the control rats; 0.5 mg/kg noradrenaline injections induced a clear RQ decrease in the former and did not influence the latters' RQ. Cold exposure was followed by a RQ decrease in both. Ganglion blocking agent administration decreased the RQ in the adapted animals and prevented it from falling in the control those. Noradrenaline is supposed to be the main but not the only factor activating lipolysis in the cold adapted animals.
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PMID:[Mechanisms of the thermogenic action of noradrenaline during adaptation to cold]. 0 Feb 57

Norepinephrine turnover rates and tyrosine hydroxylase activities were determined in the interscapular brown fat pad of the rat during cold acclimation, hyperthyroxinism, and after thyroidectomy. Rats were cold acclimated by placement in a cold room, one rat to a cage, for a period of 6 wk. Hyperthyroxinism was induced by daily subcutaneous injections of L-thyroxine (1 mg/kg) for 6 days. Norepinephrine turnover rate and enzyme activity were determined at the end of each experimental period and at 8 wk after thyroidectomy. The rate of norepinephrine turnover increased during cold acclimation and hyperthyroxinism and decreased after thyroidectomy. Cold acclimation resulted in a significant increase in tyrosine hydroxylase activity, whereas no significant effect on enzyme activity was observed in hyperthyroxinism or after thyroidectomy. None of the conditions produced a change compared to controls in the apparent Km of tyrosine hydroxylase for L-tyrosine. Cold acclimation resulted in a significant decrease in the apparent Km of tyrosine hydroxylase for pterin cofactor, whereas thyroxine treatment and thyroidectomy had no effect.
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PMID:Thyroid cold acclimation influences on norepinephrine metabolism in brown fat. 1 13

The level of plasma dopamine-beta-hydroxylase (DBH) activity in subjects at rest was found to be significantly lower in 12 patients on long-term hemodialysis than in a healthy 8-member control group: 28.3 +/- 7.2 and 13.6 +/- 7.6 IU/1, respectively (p less than 0.01). Following immersion of one hand of each subject into cold water (4 degrees C) for 1 min, a significant rise was observed in both groups, 6.1 +/- 4.8 IU/1 for the control and 1.6 +/- 1.4 IU/1 for the patient group (p less than 0.01). Upon tilting up the head of all subjects, activity in both groups increased significantly, but a markedly smaller rise was found in the patient group: 5.8 +/- 4.8 and 1.1 +/- 1.6 IU/1 for the two groups, respectively (p less than 0.01). The data suggest an autonomic nervous dysfunction in patients on long-term hemodialysis.
Nephron 1979
PMID:Autonomic nervous dysfunction in patients on long-term hemodialysis. 10 81

1 Noradrenaline (20 micrograms) and carbachol (1 microgram) injected into the anterior hypothalamus of rats at an ambient temperature of 23 degrees C evoked significant falls in core temperature and increases in tail temperature. 2 When rats were cold-stressed (4 degrees C for 90 min) or cold-acclimated (4 degrees C for 4 weeks) and the above amine injections repeated, only carbachol evoked significant falls in core temperature and neither amine increased tail temperature. 3 Central injections of noradrenaline and carbachol also evoked increases in plasma glucose concentrations but not plasma non-esterified fatty acid (NEFA) concentrations in control, acutely cold-stressed and cold-acclimated rats. 4 Although concentrations of plasma glucose and blood lactate of rats were unaffected by cold exposure to 4 degrees C for 1 to 28 days, glucose oxidation rate of both cold-stressed and cold-acclimated rats was significantly greater than in rats at 23 degrees C. Concentrations of plasma NEFA were increased after 1 to 28 days of cold exposure.
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PMID:Effects of noradrenaline and carbachol on temperature regulation of cold-stressed and cold-acclimated rats. 46 85

Heat production of isolated brown-fat cells by addition of noradrenaline and glucagon was measured in warm-acclimated control, cold-acclimated and heat-acclimated rats by use of a twin-type conduction microcalorimeter. Noradrenaline and glucagon induced maximum heat production per 10(6) cells in dose of 1 microgram/ml. Heat produced by maximum thermogenic response to glucagon was twice as much as that to noradrenaline. Thermogenic response to noradrenaline was markedly increased in cold-acclimated brown adipocytes, while it was reduced in heat-acclimated ones. Thermogenic response to glucagon was significantly reduced in heat-acclimated brown adipocytes, while it was not affected in cold-acclimated brown adipocytes.
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PMID:Thermogenic responses of brown adipocytes to noradrenaline and glucagon in heat-acclimated and cold-acclimated rats. 54 97

Effects of catecholamines on the contraction of isolated guinea-pig gallbladder induced by transmural stimulation (TM) were investigated. Tetrodotoxin and atropine prevented the TM-induced contraction. Atropine, but not tetrodotoxin, blocked the acetylcholine-induced contraction. Furthermore, the TM-induced contraction was sharply reduced during a cold storage for 1 to 4 days and then abolished 4 to 7 days later. Norepinephrine (5 X 10(-6) M) and epinephrine (4.5 X 10(-6) M) did not affect acetylcholine-induced contraction, but reduced the contractile response to TM by about 40% and 60%, respectively. Phentolamine, but not propranolol, abolished the inhibitory effects of norepinephrine and epinephrine on the contraction induced by TM. Isoproterenol and phenylephrine did not significantly modify the TM-induced contraction. These observations suggest that TM-induced contraction is produced by the release of acetylcholine from the ending of postganglionic cholinergic fibers. The possibility that norepinephrine and epinephrine act on the inhibitory alpha-adrenoreceptors in the ending of cholinergic neuron is discussed.
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PMID:[Mechanism of action of catecholamines on the electrically-stimulated, isolated guinea-pig gallbladder]. 57 30

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.
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PMID:Effects of norepinephrine on uptake and oxidation of plasma free fatty acids in cold-acclimated rats. 60 88

The highly sensitive thermometric method (1.10(-5) degrees C/mm) revealed that the heat production of single contraction of the isolated rat diaphragmal muscle with artificial hyperthyrosis (HD) is nearly double of that of the normal muscle (ND). Noradrenaline added to the inculation solution entailed a greater increase of heat production of the muscle contraction in HD and had no significant effect on ND. However, calorific effect of thyroid hormone was about twice and a half as great as that of noradrenaline. These data suggest that thyroxin acts independently in the energy regulation during the cold acclimation of the organism, and the calorific effects of both hormones can be more effectively realized just at the moment of muscle contraction.
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PMID:[Effect of thyroxine and noradrenaline on the energetics of muscle contraction]. 68 3

The effects of increasing and decreasing activity in sympathetic neurons on light (D420 = 1.05) and heavy (D420 = 1.15) populations of adrenergic vesicles have been determined. Norepinephrine (NE) was used as a marker for the soluble contents of the vesicles, and dopamine beta-hydroxylase was used as a marker for the vesicle membranes. Cold exposure was used to increase activity in the sympathetic nervous system. A 40% decrease in the NE content of the rat heart with no change in the activity of dopamine beta-hydroxylase was observed after 70 minutes at 5 degrees C. The fall in NE content was completely blocked by pretreating the animals with chlorisondamine. Separation of light and heavy populations of vesicles was achieved with linear sucrose density gradients. Cold stress of 70 minutes duration led to a marked decrease in the NE content of the light vesicles. Blocking adrenergic nerve impulses with chlorisondamine resulted in an increase in total NE in the heart but had no effect on dopamine beta-hydroxylase activity. The initial effect of chlorisondamine was to increase the NE content of the light vesicles. The administration of alpha-methyl-p-tyrosine for 6 hours caused an approximately equal loss of NE from both vesicle populations. The decrease in total heart NE was about 25% and could be prevented by pretreating the animals with chlorisondamine. These results suggest that the light vesicle fraction is involved in the rapid or short-term responses to changes in nerve impulse frequency. Changes in the NE content of the heavy vesicles in rat heart were seen only after longer times, suggesting that these particles may function only as auxiliary storage sites for the neurotransmitter.
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PMID:Differential effects of nerve impulses on adrenergic storage vesicles in rat heart. 93 1

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.
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PMID:Effects of norepinephrine and thyroxine on the turnover rate of plasma free fatty acids. 122 7


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