Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:4.6.1.1 (adenylate cyclase)
19,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Quantitative studies of the action of theophylline and papaverine were performed in rat epididymal fat pads, both on the lipolytic effect and on the activity of phosphodiesterase, adenylate cyclase and protein kinase. Papaverine, a stronger inhibitor of phosphodiesterase than theophylline, did not produce lipolysis. The maximum lipolytic effect (glycerol release) of theophylline was much higher than that of epinephrine and nearly approached the effect exerted by dibutyryl cyclic AMP. While theophylline potentiated or was without any effect on lipolysis produced by epinephrine and dibutyryl cyclic AMP, papaverine at concentration 10- minus 3 M reduced the effect of both drugs as well as of theophylline by 90 per cent. These concentrations of papaverine also strongly inhibited the activity of adenylate cyclase. Neither papaverine nor theophylline prevented the activation of protein kinase by cyclic AMP. The data suggest that the lack of a lipolytic effect of papaverine migth be caused by a combination of its inhibitory effect on adenylate cyclase and direct inhibition of activation of triglyceride lipase.
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PMID:The absence of stimulation of lipolysis by papaverine, a strong inhibitor of phosphodiesterase. 16 81

Ethanol and other alcohols stimulate adenylate cyclase activity in various tissues and potentiate its stimulation by some hormones. This effect, however, usually requires a high alcohol concentration. In some cases, an unknown substance, different from cyclic AMP, was formed from ATP in the presence of an alcohol and mimicked stimulation of adenylate cyclase. Ethanol inhibits phosphodiesterase activity in some tissues. In the brain, only the low affinity enzyme of pons-medulla region is inhibited. ATP levels and ATPase activities are affected by ethanol treatment and this can lead to secondary changes of the cyclic AMP levels. Cyclic AMP levels in the brain and liver are decreased by acute ethanol administration while levels in other organs are unchanged. High doses of ethanol inhibit the postdecapitation-induced rise of cyclic AMP level in the brain while low ethanol doses potentiate the postdecapitation rise of cyclic AMP in the lower brain stem. Chronic ethanol administration increases basal adenylate cyclase activity and cyclic AMP levels, and decreases stimulation of adenylate cyclase by norepinephrine in the brain. In contrast, the stimulation of cyclic AMP formation by norepinephrine and other biogenic amines is increased in the brain of ethanol-withdrawn animals. Chronic administration of ethanol affects also cyclic AMP levels and cyclic AMP formation in some peripheral organs. Cyclic AMP might be involved in ethanol-induced fatty liver, since it activates hepatic lipase and might also participate in the fatty acid oxidation.
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PMID:Interactions of ethanol with cyclic AMP. 16 56

Human chorionic somatomammotropin extracted and purified from placenta at term was proved to have a lipolytic action in the epididymal fat pad of rats. The following mechanism appears to be involved in the lipolytic action of the hormone; human chorionic somatomammotropin activates adenyl cyclase, thereby increasing the concentration of cyclic AMP in the tissue, which, in turn, activates protein kinase to lead to the activation of hormone sensitive lipase.
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PMID:Lipolytic action of human chorionic somatomammotropin. 16 57

Adenine requiring mutants of Serratia marcescens SM-6-F'lac+ have been found to grow well in minimal-glucose medium solely supplemented with cAMP. From one of these ade strains double mutants (called ade cpd) were isolated which could no longer utilize cAMP but which still grew on 5'AMP. Dialyzed cell extracts (soluble fraction) of the double mutants, assayed for cAMP phosphodiesterase, were unable to hydrolyze cAMP whereas cell extracts of the parental strains yielded 5'AMP at a rate of 1.6-2.0 mumoles min-1 mg-1 protein. The loss of the phosphodiesterase activity in S. marcescens cpd W 1181 did not cause an accumulation of large amounts of cAMP as was found for the diesterase-negative mutant AB257pc-1 of Escherichia coli. The induced synthesis of beta-galactosidase in mutant cpd W 1181 showed about the same sensitivity to transient and permanent catabolite (glucose) repression as the corresponding cpd+ strain. Starting from S. marcescens cpd W 1182 three independent double mutants (called cpd cya) were isolated which required exogenous cAMP for utilizing various carbohydrates as carbon source, for motility and for the formation of extracellular lipase and the red pigment prodigiosine. The intracellular concentration of cAMP in these mutants, grown in nutrient broth, was 40-60% of that of the parental strain which is about 4 x 10(-4) M. However, the adenylate cyclase in cell extracts of the mutants W 1237 and W 1270 was like that of the corresponding cya+ strain (about 2 x 10(-2) mumoles min-1 mg-1 protein).
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PMID:Mutants of Serratia marcescens lacking cyclic nucleotide phosphodiesterase activity and requiring cyclic 3',5'-AMP for the utilization of various carbohydrates. 16 32

An adenylate cyclase activity (AC) was found in guinea pig brown adipose tissue (BAT), since the tissue's apparition. This enzymatic activity increased during the development and showed high values at the end of gestation. An increase of AC units per cell was observed, in addition to the cell multiplication. A norepinephrine stimulation of AC activity was observed at the end of gestation : this regulating action disappeared in the first days of extrauterine life. Neither glucagon nor ACTH had any regulating role upon AC activity during fetal and newborn life. The basal lipolytic activity which was observed in BAT of fetuses (61rst day) and neonate dramatically around the 15th day. A potent lipolysis activation by norepinephrine was observed, but only after birth. The correlation observed between these enzymatic activities in presence of norepinephrine seems to indicate that the AC/lipase system was involved in the neonatal thermogenesis of guinea pigs.
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PMID:[Adenylate cyclase/Lipase. Hormone receptor induction]. 17 89

The large increase in cyclic AMP accumulation by rat white fat cells seen in the presence of lipolytic agents plus methylxanthines and adenosine deaminase was markedly inhibited by lactate. However, lipolysis was unaffected by lactate. Octanoate, hexanoate, heptanoate, and beta-hydroxybutyrate inhibited both cyclic AMP accumulation and lipolysis by rat fat cells. The mechanism by which these acids inhibit lipolysis differs from that for long chain fatty acids such as oleate. Oleate directly inhibited triglyceride lipase activity of homogenized rat adipose tissue. In contrast, octanoate, beta-hydroxybutyrate, and lacatate had no effect on triglyceride lipase activity. Hormone-stimulated adenylate cyclase activity of rat fat cell ghosts was inhibited by oleate and 4mM octanoate but not by 1.6 mM octanoate, heptanoate, hexanoate, beta-hydroxybutyrate or lactate. None of the acids affected the soluble protein kinase activity of rat adipose tissue. There was no stimulation by lactate, butyrate, beta-hydroxybutyrate, or octanoate of the soluble or particulate cyclic AMP antilipolytic action of a short chain acid such as octanoate or hexanoate was not accompanied by any drop in total fat cell ATP. The mechanism by which lactate lowers cyclic AMP but not lipolysis remains to be established.
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PMID:Inhibition of adenosine 3':k'-monophosphate accumulation white fat acids, lactate, and beta-hydroxybutyrate. 18 3

The liberation of arachindonate in the thyroid occurs at the expense of two distinct pools of precursors. (1) the phosphatidylinositol through a process Ca2+-dependent and cyclic AMP-independent; and (2) the triglycerides by a cyclic AMP-dependent lipase, in which the involvement of cyclic AMP-dependent protein kinase has not yet been determined. The "PI pool" or "paracyclic AMP pool" is mobilized very rapidly by large doses of TSH but its physiological significance can be discussed. The "triglyceride pool" or "post-cyclic AMP pool" is mobilized more slowly by small doses of TSH and seems not to be implicated in the acute TSH stimulation of adenylate cyclase. The "post-cyclic AMP pool" of prostaglandins would be very important as third messenger or as "long-acting TSH hormone". Some recent works of Boeynaems and Van Sande (16) and Madaoui et al. (17) on the thyroid support this hypothesis, as aspirin or indomethacin inhibits DBc-AMP stimulation of glucose oxydation, iodine organification, or thyroid hormone secretion. On the other hand, in the absence of prostaglandin synthesis, TSH still stimulates the adenylate cyclase, which means that prostaglandins are not obligatory intermediates of hormonal action on cyclic AMP production. In conclusion, these results show a TSH action in the thyroid on the release of fatty acids, precursors of PG's, from their lipidic stores. Nevertheless, a second control step is not excluded in conversion of cyclic endoperoxide to PGE or PGFalpha.
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PMID:Stimulation by TSH of prostaglandin synthesis in pig thyroid. 18 42

Adipose-tissue triacylglycerol is the major energy store in man. The physiological importance and biochemical mechanism of the hormonal control of lipolysis in white adipose tissue is reviewed. Rates of lipolysis and fatty acid release observed when adipose tissue is incubated in vitro are compared with rates of triacylglycerol turnover in man. It appears that enhanced rates of lipolysis in vivo, for example during fasting and exercise, may be a substantial fraction of the maximum obtainable by hormone stimulation in vitro. There is considerable species variation in the hormonal sensitivity of adipose tissue. Some hormones that stimulate lipolysis in vitro may not be significant lipolytic agents at physiological concentrations in vivo. In man and rat, the most important acutely acting lipolytic and anti-lipolytic hormones are catecholamines and insulin respectively. The sympathetic nervous system may play a role at least as important as circulating catecholamines in the mobilization of stored triacylglycerol. The effects of acute lipolytic hormones are modulated in the long term by corticosteroids and thyroid hormone. Stimulation of lipolysis is believed to be mediated by the increased intracellular cyclic AMP concentration that occurs after interaction of hormones with specific receptors in the plasma membrane. The properties of membrane receptors, adenylate cyclase, cyclic AMP phosphodiesterase, cyclic AMP-dependent protein kinase and triacylglycerol lipase, as studied in rat and human adipose tissue, are discussed. Several features of the action of lipolytic hormones in vitro are difficult to account for by the hypothesis that cyclic AMP is the only "second messenger" regulating lipase activity. These include anomalous effects of hormones at high concentrations and the possible existence of feedback inhibition limiting the accumulation of cyclic AMP and the stimulation of lipolysis. The mechanism of the anti-lipolytic action of insulin is at present unknown.
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PMID:Hormonal control of adipose-tissue lipolysis. 21 67

Bilirubin (0.45 mM) inhibited lipolysis and stimulated [1-14C]glucose oxidation by rat fat cells in the presence of an equimolar concentration of bovine serum albumin. Bilirubin was an insulinlike agent with respect to inhibition of lipolysis and stimulation of glucose oxidation. There was a marked inhibition of adenylate cyclase activity of fat cell ghosts by 0.001--0.1 mM bilirubin in the absence of albumin, which was largely reversed by the addition of albumin. Although both bilirubin and free fatty acids bind to albumin, the primary binding sites appear to be separate. The effects of bilirubin at a molar ratio to albumin of 2 or less were not influenced by free fatty acid-to-albumin ratios up to 3. Triglyceride lipase activity of partially purified rat fat cell homogenates was inhibited by bilirubin in the presence of an equimolar concentration of bovine albumin. These data indicate that the antilipolytic action of bilirubin is probably due to direct inhibition of triglyceride lipase through a mechanism that does not involve competition with free fatty acids for binding to albumin.
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PMID:Effects of bilirubin on fat cell metabolism and lipolysis. 51 47

With histochemical methods the distribution of some enzymes and metabolic substances in the epidermal peelings of Phaseolus mungo, Lathyrus sativus, and Opuntia elatior under light and dark conditions is examined. Dehydrogenases oxidases, transferases and hydrolases were studied. Fluctuations in the activity of hydrolases, especially, acid phosphatase, lipase, glucose-6-phosphatase, adenosine triphosphatase, dehydrogenases and transferases were observed during light and dark conditions. The role of such fluctuations in relation to stomatal regulation is discussed. Based on the present studies the following is suggested; stomatal opening and closing is related to structural and metabolic changes, and these changes are brought about by sugar gradients in the guard cells; light is enhancing the synthesis of sugars and some hormones, and besides this it stimulates membrane bound adenyl cyclase and release of cyclic AMP which affects the permeability; subsidiary cells actively participate in the stomatal physiology. Lysosomal hydrolytic enzymes like acid phosphatase are actively involved in catabolic phase of normal guard cells metabolism and regulate the osmotic pressure of the guard cells.
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PMID:Histochemical studies in stomatal apparatus of Phaseolus mungo Linn, Lathyrus sativus Linn and Opuntia elatior Mill. 59 72


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