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)

Daily intraperitoneal injection of cadmium chloride (0.25 or 1 mg/kg) for 21 or 45 days into rats significantly stimulated the activities of hepatic pyruvate carboxylase, phosphoenolpyruvate carboxykinase, fructose-1, 6-diphosphatase, and glucose-6-phosphatase, increased the concentrations of glucose and urea in the blood, and decreased the levels of glycogen in the liver. Whereas chronic cadmium treatment failed to alter adenosine-3',5'-monophosphate phosphodiesterase (phosphodiesterase) activity, the endogenous levels of cyclic AMP (cAMP) and the activity of basal- and fluoride-stimulated forms of hepatic adenylate cyclase (AC) were markedly increased in cadmium-injected animals. Treatment with the higher dose (1.0 mg/kg) of cadmium chloride for 45 days produced greater metabolic alterations in hepatic tissue than those seen with the lower dose (0.25 mg/kg) given for a shorter period of time (21 days). Discontinuation of cadmium administration for 14 days in rats previously injected with cadmium chloride (1 mg/kg per day) for 21 days, failed to reverse the observed changes in hepatic cAMP or carbohydrate metabolism. A similar persistence of metabolic alterations was noted in rats treated with cadmium (1 mg/kg per day) for 45 days and subsequently maintained without additional treatment for 28 days. Administration of an acute dose of cadmium chloride (60 mg/kg) decreased hepatic phosphodiesterase activity and glycogen content 1 h after the injection. In addition, acute cadmium exposure increased blood glucose, serum urea, and hepatic cAMP levels, and produced an augmentation of basal- and fluoride-activated AC. However, the activities of various hepatic gluconeogenic enzymes remained unaffected in animals given an acute dose of cadmium chloride (60 mg/kg). Data provide evidence that suggests that the gluconeogenic potential of liver is markedly enhanced following chronic exposure to cadmium and that the cadmium-induced changes in carbohydrate metabolism may be associated with an enhanced synthesis of cAMP. In addition, the present study shows that the cadmium-induced metabolic alterations persist even after the cessation of cadmium treatment for a period of 28 days.
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PMID:Response of hepatic carbohydrate and cyclic AMP metabolism to cadmium treatment in rats. 16 49

Cadmium, in addition to producing a variety of toxic manifestations, is known to accumulate in certain "target" organs which include liver and kidney where histological and functional damage becomes apparent. The daily intraperitoneal injection of cadmium chloride for 21 or 45 days stimulated the activities of hepatic pyruvate carboxylase, phosphoenolpyruvate carboxykinase, fructose-1, 6-diphosphatase and glucose-6-phosphatase elevated blood glucose and urea, and lowered hepatic glycogen in rats. Whereas chronic Cd treatment failed to alter adenosine-3', 5'-monophosphate phosphodiesterase (PDE) activity, cyclic AMP (cAMY and the activity of basal and fluoride-stimulated forms of hepatic adenylate cyclase (AC) were markedly increased. However, the cAMP binding to hepatic protein kinase was decreased as was the kinase activity ration. An acute dose of Cd decreased hepatic glycogen content and increased blood glucose, serum urea, and hepatic cAMP. Chronic exposure to Cd induced adrenal hypertrophy and augmented adrenal norepinephrine and epinephrine as well as the activity of adrenal tyrosine hydroxylase. This treatment decreased prostatic and testicular weights of mature rats. Although cAMP as well as AC activity of the prostate gland were reduced, cAMP binding to the prostatic protein kinase was increased as was the activity of the cAMP-dependent form of the enzyme. Testicular AC and PDE activities, however, were stimulated, although cAMP remained unaffected. Whereas the activities of the cAMP-dependent and the independent forms of testicular protein kinase were significantly depressed, the binding of cAMP to protein kinase from testes of Cd-treated rats was not affected. In most cases, the observed metabolic alterations persisted up to 28 days on cessation of Cd administration. Subacute Cd treatment suppressed pancreatic function as evidenced by lowered serum immunoreactive insulin (IRI) in presence of hyperglycemia, as well as by partial inhibition of phentolamine-stimulated increases in serum IRI. Although chronic Cd treatment failed to alter the concentration of brain stem norepinephrine and cerebrocortical acetylcholine esterase activity, serotonin levels of brain stem were depressed and the concentration of striatal dopamine and cerebrocortical acetylcholine were significantly elevated when compared with the values seen in control nonexposed animals.
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PMID:Aspects of the biochemical toxicology of cadmium. 17 84

The effects of chronic oral ingestion of lead in doses ranging from 20-80 ppm were compared with those seen after the subacute exposure of rats to a 10 mg/kg daily dose of the heavy metal for 7 days. Irrespective of the treatment regimen used, lead treatment significantly increased the activities of renal pyruvate carboxylase, phosphoenolpyruvate carboxykinase, fructose 1,6-diphosphatase and glucose 6-phosphatase. The observed enhancement of kidney gluconeogenic enzymes in chronically treated animals was associated with a stimulation of the adenylate cyclase-cyclic AMP system, a rise in blood blucose and urea as well as a depression in hepatic glycogen and serum immunoreactive insulin (IRI) levels. In contrast, subacute exposure to lead failed to significantly alter cyclic AMP metabolism and the concentrations of liver glycogen, blood glucose, serum urea or IRI. Whwereas the insulinogenic index (the ratio of serum IRI to blood glucose concentration) was markedly suppressed in chronically treated rats, this ratio remained within normal limits following subacute exposure to the heavy metal. However, a marked decrease in the insulinogenic index was observed in subacutely treated rats 15 min after the administration of a glucose load. The data provide evidence to show that increased glucose synthesis as well as suppressed pancreatic function may be responsible for lead-induced disturbances in glucose homeostasis.
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PMID:Effects of subsacute and chronic lead treatment on glucose homeostasis and renal cyclic AMP metabolism in rats. 18 14

Isolated sheep hepatocytes were used to obtain estimates of kinetic parameters, identify substrate preference and interactions and study regulation of gluconeogenesis. Respective Vmax estimates for propionate, pyruvate and alanine conversion to glucose were 59.5, 12.8 and 21.5 mol glucose formed X (h X g dry weight)-1. Respective KS estimates for propionate and pyruvate were 1 mM and 18 to 40 microM. Rates of lactate utilization varied among cell preparations, possibly because of loss of lactate dehydrogenase during isolation. Dihydroxyacetone and glycerol were utilized for glucose synthesis at similar rates of 8.6 and 8.7 mumol glucose formed X (h X g dry weight)-1, respectively. Respective rates of glucose synthesis from 5 mM fructose and 10 mM galactose were 63.2 and 31.4 mumol X (h X g dry weight)-1. Maximum rates of pyruvate carboxylase and phosphoenolpyruvate carboxykinase were estimated to be 101.6 and 160.4 mumol substrate converted X (h X g dry weight)-1, respectively. Neither butyrate nor acetate accelerated gluconeogenesis from propionate while acetate increased glucose synthesis from pyruvate, presumably through activation of pyruvate carboxylase. Glucagon stimulated gluconeogenesis from propionate. Dibutyrylcyclic AMP mimicked the effect of glucagon, implying that the glucagon effect is translated via the adenyl cyclase system as in rats. The kinetic parameters established in these experiments should be useful in future experiments and in computer modeling analyses of ruminant liver and whole animal metabolism where Michaelis-Menten type equations are widely used.
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PMID:Gluconeogenesis in isolated lamb hepatocytes. 381 90

The possibility whether alterations in the cyclic AMP-adenylate cyclase-phosphodiesterase system play a role in the action of 1,1,1-trichloro-2,2-bis-(p-chlorophenyl)ethane (DDT) on hepatic and renal carbohydrate metabolism was investigated. Administration of exogenous cyclic AMP (10mg/100g) was found to mimic the action of DDT which enhanced the activities of pyruvate carboxylase, phosphoenolpyruvate carboxylase, fructose 1,6-diphosphatase and glucose 6-phosphatase in both liver and kidney cortex, elevated the concentration of blood glucose and urea and decreased the amount of hepatic glycogen. Treatment with theophylline augmented the effects of a submaximal dose of this halogenated hydrocarbon on serum urea and glucose as well as the key gluconeogenic enzymes in liver and kidney cortex. Addition of DDT in vitro to liver and kidney homogenates resulted in a significant enhancement of adenylate cyclase activity. Hepatic and renal slices from rats already treated with DDT displayed an increased ability to convert [(3)H]adenosine into cyclic [(3)H]AMP. Whereas kidney-cortex slices excised from rats given caffeine and DDT produced an even greater amount of cyclic [(3)H]AMP, imidazole, propranolol and hydrazine prevented the insecticide-stimulated rise in cyclic nucleotide production. In contrast, prostaglandin E(1) failed to exert any significant effect on DDT-induced increases in cyclic [(3)H]AMP synthesis from radioactive adenosine. The present study and our previous findings (Kacew & Singhal, 1973e) support the concept that the DDT-induced alterations in carbohydrate metabolism of liver and kidney cortex may be related to an initial stimulation of the cyclic AMP-adenylate cyclase system in these tissues.
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PMID:Role of cyclic adenosine 3':5'-monophosphate in the action of 1,1,1-trichloro-2,2-bis-(p-chlorophenyl)ethane (DDT)on hepatic and renal metabolism. 437 84