scholarly journals The effect of thyroid hormone on bile salt-independent bile flow and Na+, K+ -ATPase activity in liver plasma membranes enriched in bile canaliculi.

1976 ◽  
Vol 57 (4) ◽  
pp. 1009-1018 ◽  
Author(s):  
T J Layden ◽  
J L Boyer
Keyword(s):  
Thyroid Hormone ◽  
Atpase Activity ◽  
Bile Salt ◽  
Bile Flow ◽  
Plasma Membranes ◽  
Bile Canaliculi ◽  
Liver Plasma Membranes

Thyroid hormone-catecholamine interrelationship during cold acclimation in rats Compensatory role of catecholamine for altered thyroid states

1986 ◽  
Vol 113 (4) ◽  
pp. 536-542 ◽  
Author(s):  
Tamotu Sato ◽  
Eiichi Imura ◽  
Akisato Murata ◽  
Noboru Igarashi
Keyword(s):  
Thyroid Hormone ◽  
Cold Acclimation ◽  
Cold Exposure ◽  
Plasma Membranes ◽  
Body Weight Gain ◽  
The Body ◽  
Hormone Deficiency ◽  
Adult Rats ◽  
Liver Plasma Membranes ◽  
Brown Adipose

Abstract. Effects of hyper- and hypothyroidism on catecholamine (CA) metabolism in the brain, adrenal glands, liver, and brown adipose tissue (BAT) were studied in adult rats during cold acclimation. Hypothyroidism was induced by the administration of propylthiouracil (PTU) and hyperthyroidism by the injection of thyroxine (T4). After 2 weeks of treatment, they were exposed to cold (5°C) and sacrificed after 1 or 4 weeks. Although the body weight gain of PTU-treated rats were markedly impaired, the body temperature was maintained within normal range. They had increased cerebral dopamine, adrenal CA and BAT norepinephrine (NE) contents, enhanced cerebral tyrosine hydroxylase and adrenal dopamine β-hydroxylase (DBH) activities and elevated [3H]dihydroalprenolol (DHA) binding to liver plasma membranes (P <0.01 vs controls). T4-treated rats showed an increased brain and adrenal CA only after cold exposure. The BAT NE content, DHA binding to liver plasma membranes, and [3H]guanosine diphosphate binding to BAT mitochondria were reduced by 30 to 50% from control values after 4 weeks of cold exposure. These results indicate that during cold acclimation, 1) thyroid hormone deficiency is associated with an accelerated CA synthesis and release, which results in an enhanced BAT thermogenesis, and 2) the hyperthyroid state suppresses CA release, hepatic DHA binding, and BAT heat production. Thus, there is a close metabolic interrelationship between thyroid hormone and CA during exposure to cold. CA appears to ameliorate thyroid hormone excess or deficiency.

scholarly journals Calcium-Binding Properties and ATPase Activities of Rat Liver Plasma Membranes

1974 ◽  
Vol 64 (1) ◽  
pp. 104-126 ◽  
Author(s):  
Anne-Marie Chambaut ◽  
Françoise Leray-Pecker ◽  
Gérard Feldmann ◽  
Jacques Hanoune
Keyword(s):  
Atpase Activity ◽  
Rat Liver ◽  
Binding Sites ◽  
Calcium Binding ◽  
Plasma Membranes ◽  
Atp Hydrolysis ◽  
Ph Dependence ◽  
Classical Energy ◽  
Liver Plasma Membranes ◽  
Specificity And Sensitivity

Plasma membranes from rat liver purified according to the procedure of Neville bind calcium ions by a concentration-dependent, saturable process with at least two classes of binding sites. The higher affinity sites bind 45 nmol calcium/mg membrane protein with a KD of 3 µM. Adrenalectomy increases the number of the higher affinity sites and the corresponding KD. Plasma membranes exhibit a (Na+-K+)-independent-Mg2+-ATPase activity which is not activated by calcium between 0.1 µM and 10 mM CaCl2. Calcium can, with less efficiency, substitute for magnesium as a cofactor for the (Na+-K+)-independent ATPase. Both Mg2+- and Ca2+-ATPase activities are identical with respect to pH dependence, nucleotide specificity and sensitivity to inhibitors. But when calcium is substituted for magnesium, there is no detectable membrane phosphorylation from [γ-32P] ATP as it is found in the presence of magnesium. The existence of high affinity binding sites for calcium in liver plasma membranes is compatible with a regulatory role of this ion in membrane enzymic mechanisms or in hormone actions. Plasma membranes obtained by the procedure of Neville are devoid of any Ca2+-activated-Mg2+-ATPase activity indicating the absence of the classical energy-dependent calcium ion transport. These results would suggest that the overall calcium-extruding activity of the liver cell is mediated by a mechanism involving no direct ATP hydrolysis at the membrane level.

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