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)

Decapsulated testes from adult rats were digested with collagenase, and the fraction enriched in germinal and Leydig cells was applied to a 0-4% continuous metrizamide gradient and centrifuged. This leads to separation of a germinal cell fraction and two putative Leydig cell populations that bind human choriogonadotropin, but only one of which responds to the gonadotropin with marked increase in testosterone production. Adenylate cyclase activity was present in these three fractions, and Mn2+ was more effective than Mg2+ as a divalent cation. The adenylate cyclase activity associated with the germinal cell fraction was just marginally stimulated by fluoride and by the non-hydrolyzable GTP analog 5'-guanylimidodiphosphate, while that associated with the Leydig cell populations was stimulated to a greater degree depending upon the type of divalent cation. Only the Leydig cell populations exhibited marked human choriogonadotropin-sensitive stimulation of adenylate cyclase activity in the presence of 5'-guanylimidodiphosphate above that observed with the GTP analog alone. These results suggest the presence of distinct adenylate cyclases in adult rat testis and indicate that both populations of Leydig cells are capable of producing cyclic AMP in response to gonadotropins such as human choriogonadotropin.
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PMID:Demonstration of distinct forms of testicular adenylate cyclases associated with germinal and Leydig cell fractions. 628 12

The biological properties of chemically deglycosylated human choriogonadotropin (DG-hCG) preparations were examined in collagenase-dispersed rat interstitial cells in vitro. Despite effective receptor binding activity in membrane preparations, DG-hCG failed to induce cyclic AMP accumulation in the cells when incubated in the presence or absence of a phosphodiesterase inhibitor. The steroidogenic ability as assessed by testosterone accumulation in the medium was less than 0.5% of the native hormone with a failure to attain maximal steroid production. Time course experiments have revealed that altered kinetics could not be responsible for the loss of hormone response. Consistent with its property of good receptor binding and poor cell activation, DG-hCG antagonized the action of native hCG. When added to the cells at the same time, DG-hCG inhibited the action of a maximal stimulatory dose of hCG in a dose-dependent manner. Inhibition of cyclic AMP accumulation was complete whereas inhibition of steroidogenesis was about 75%. DG-hCG had no effect on the stimulatory action of cholera toxin in interstitial cells or that of follitropin in rat seminiferous tubular preparations. The data suggest that DG-hCG has a conformation conductive for effective interaction with the receptor, but its ability to activate the adenylate cyclase is either lost or weakly expressed.
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PMID:Hormonal antagonistic properties of chemically deglycosylated human choriogonadotropin. 629 9

Medullary and cortical tubular cells were prepared from rat kidneys with collagenase treatment. Arginine vasopressin (AVP) stimulated cyclic AMP production both in medullary and cortical cells with a dose-response relationship at concentrations ranging from 10 microU/ml to 10 mU/ml, whereas parathyroid hormone (PTH) and calcitonin did only in the latter. Using this medullary cell system, effects of acute changes in endogenous plasma AVP levels in vivo on its cyclic AMP responsiveness to AVP (10 mU/ml) in vitro were examined. Acute elevation of plasma AVP levels induced by ip injection of 20% (w/v) polyethylene glycol-isotonic saline solution 3 h prior to sacrifice resulted in a 33% decrease in cyclic AMP responsiveness to AVP (desensitization). More prolonged elevation of plasma AVP levels by water restriction for 48 h, on the other hand, increased the responsiveness by 38 to 81%, which was restored to basal levels by ad libitum intake of water for another 48 h (positive feedback regulation). These maneuvers did not alter the cyclic AMP responsiveness to PTH (10 micrograms/ml) in cortical cells. The results suggest that AVP-stimulated adenyl cyclase in rat renal medulla may be regulated by changes in endogenous AVP levels even within the physiological range.
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PMID:Altered cyclic AMP responsiveness to vasopressin in rat renal medullary dispersed cells by acute elevation of endogenous vasopressin. 629 51

We have used cultured trypsin-collagenase-dispersed cells from uteri of 21-day-old rats to investigate the mechanism of control of uterine motility by the beta-adrenergic receptor. After 5 to 7 days in RPMI 1640 the cells started to assume some of the morphological characteristics of smooth muscle cells. When cultures were incubated with 45Ca2+ for 3 h then washed free of isotope and incubated in medium with unlabeled Ca2+, efflux from the prelabeled intracellular pools was linear for up to 60 min. The potent beta-adrenergic agonist isoproterenol had a rapid effect on the rate of efflux and increased it almost sevenfold. Isoproterenol's effect was blocked by propranolol and could be duplicated by the addition of 8-bromo-adenosine 3',5'-cyclic monophosphate or cholera toxin. The cultured myometrial cells had adenylate cyclase properties similar to those of intact muscle strips when these were determined by the conversion of radioactive substrate (alpha-32P-ATP) to 32P-cAMP using a broken-cell preparation. Adenylate cyclase was sensitive to stimulation by GTP and by isoproterenol in the presence but not in the absence of GTP. Adenylate cyclase was also sensitive to stimulation by Ca2+ in the absence of GTP. We conclude that the primary cultures had the properties expected of smooth muscle cells including beta-adrenergic receptors that were coupled to a physiologically important function, Ca2+ flux. The beta-adrenergic receptor's effect on Ca2+ flux was cAMP mediated, and the divalent cation may also regulate its rate of flux by an effect on Ca2+-sensitive cAMP production.
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PMID:beta-Adrenergic catecholamine-dependent properties of rat myometrium primary cultures. 630 58

We have studied the compartmentation of cyclic AMP action in purified ventricular cardiomyocytes prepared by collagenase perfusion of adult rabbit hearts. Incubation of purified adult myocytes with 1 microM isoproterenol causes rapid accumulation of intracellular cyclic AMP in both soluble (2.3 leads to 7.7 pmol/ mg of protein) and particulate (3.0 leads to 9.2) fractions of cell homogenates (3000 X g for 5 min), increases in the total activity and activity ratio of soluble cyclic AMP-dependent protein kinase (0.21 leads to 0.66), a decrease in protein kinase activity remaining in the particulate fraction (47 leads to 30%), and an increase in the activity ratio of glycogen phosphorylase (0.15 leads to 0.47). Incubation of myocytes with 10 microM prostaglandin E1 (PGE1) leads to a comparable increase in soluble cyclic AMP (2.3 leads to 5.8 pmol/mg of protein) and activation of soluble cyclic AMP-dependent protein kinase (0.21 leads to 0.39) but does not result in any change in cAMP or protein kinase in the particulate fraction and fails to cause an activation of glycogen phosphorylase. PGE1 does not inhibit the effects of isoproterenol; when myocytes are incubated with both isoproterenol and PGE1, the accumulation of cyclic AMP, activation of cAMP-dependent protein kinase and phosphorylase b leads to a conversion are equal to that achieved with isoproterenol alone. Perturbation of cellular calcium using the ionophore A23187, verapamil, or high or low extracellular calcium did not alter the ability of isoproterenol to cause activation of particulate cAMP-dependent protein kinase or influence the inability of PGE1 to do so. Activation of adenylate cyclase by forskolin (30 microM) caused immediate activation of both soluble and particulate cAMP-dependent protein kinase leading to rapid activation of phosphorylase. We conclude that the hormonally specific compartmentation of cyclic AMP and cAMP-dependent protein kinase that occurs in intact heart (Hayes, J. S., Brunton, L. L., Brown, J. H., Reese, J. B., and Mayer, S. E. (1979) Proc. Natl. Acad. Sci. U.S.A. 76, 1570-1574) is not explained on the basis of cellular heterogeneity but has a subcellular basis within the cardiomyocyte.
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PMID:Compartments of cyclic AMP and protein kinase in mammalian cardiomyocytes. 630 96

Microvessels (capillaries) were isolated in pure form from rabbit ventricle by a process which involved fine mincing of the tissue, repeated incubation with collagenase to effect cell dispersal, passage of the suspended cells over a column of glass beads, and finally concentration of the capillary fraction on a step-wise sucrose gradient. Adenylate cyclase in the capillary preparation was stimulated by beta adrenergic agonists in a potency order which suggested coupling to a beta 2 subtype adrenergic receptor. Catecholamine-stimulated activity was antagonized by methoxamine, but this did not seem to be mediated through alpha adrenergic receptor activation, since it was not reversed by the alpha adrenergic antagonist phentolamine. Adenylate cyclase was stimulated by adenosine and several adenosine analogs in a potency order which suggested enzyme coupling to a stimulatory A2 receptor. Prostaglandins were also effective stimulators of enzyme activity, those of the E and A series being more potent than members of the F series. It is possible that these agents may exert their physiological actions on the microvasculature via cyclic AMP formed in response to activation of adenylate cyclase.
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PMID:Heart microvessels: presence of adenylate cyclase stimulated by catecholamines, prostaglandins, and adenosine. 631 74

Experiments were conducted to determine if methylation is a part of the mechanism by which luteinizing hormone (LH) and epinephrine stimulate progesterone production by dispersed bovine luteal cells. Corpora lutea (CL) were collected from 24 Holstein heifers on Day 10 of the estrous cycle and dispersed with collagenase. Net progesterone accumulation, representing total progesterone synthesized by 10(6) cells during a 2-h incubation was determined. Cells from 7 CL were treated with 0 and 5 ng LH, in the presence and absence of methylation inhibitor, S-adenosyl-homocysteine (SAH, 1 mM). LH-stimulated progesterone production was inhibited (P less than 0.05) in the presence of SAH(209 +/- 19 vs. 119 +/- 7 ng/10(6) cells). In the absence of LH, progesterone production was unaffected (87 +/- 22 vs. 68 +/- 28) by SAH. Cells from 4 CL were treated with 10 micrograms epinephrine or 10 micrograms isoproterenol with and without SAH. Both epinephrine and isoproterenol-stimulated progesterone production was inhibited (P less than 0.05) by the presence of SAH (204 +/- 24 vs. 125 +/- 18 and 198 +/- 15 vs. 130 +/- 8). Progesterone production by cells from 4 CL was unaffected by the presence of SAH when treated with Medium 199 (M199) (75 +/- 32), 10 micrograms cholera toxin, which directly stimulates adenylate cyclase on the cytoplasmic side of plasma membranes (168 +/- 19), or 3 mM dibutyryl cAMP (210 +/- 40).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Methylation in bovine luteal cells as a regulator of luteinizing hormone action. 631 96

Bone cells released from perinatal rat calvaria by digestion with clostridial peptidase were separated into two distinct populations (designated types B and C) by equilibrium density centrifugation on a two-step gradient of Percoll. They were extensively characterized by light and electron microscopy and for behaviour in culture, acid and alkaline phosphatase activity, collagen synthesis, collagenase secretion and adenylate cyclase response to parathyroid hormone (PTH) and calcitonin. Type C cells were predominantly large with up to seven nuclei and an unusual cytoplasmic appearance in cytocentrifuge preparations. They did not proliferate in culture and we have established culture conditions which prevented their overgrowth by contaminating proliferative cells. In culture these cells had low alkaline and high acid phosphatase and high aryl sulphatase activity, and synthesized little collagen. In contrast type B cells were mostly smaller and many had irregular cytoplasmic projections. In culture they became polygonal in shape, proliferated rapidly, and reached confluence in 4-5 days. These were low in aryl sulphatase and acid phosphatase, high in alkaline phosphatase activity, and synthesized labelled collagen actively with [3H]proline and ascorbic acid included in the culture medium. The two cell population were found to differ in culture in two important further respects. First, the type C cells showed an adenylate cyclase response to calcitonin but not to PTH, while the converse was true for type B cells; this was so over at least a 20-fold range of isobutylmethyl xanthine concentration. Secondly, type C cells in culture secreted an active collagenolytic enzyme. Type B cells secreted much lower levels of a predominantly latent collagenase which required activation by mersalyl. Co-culture of type C and type B cells led to a marked reduction in the content of active collagenase in the culture medium.
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PMID:Separation of two bone cell populations from fetal rat calvaria and a study of their responses to parathyroid hormone and calcitonin. 631 50

Renal cells from Vitamin D-deficient and 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3]-repleted chicks were isolated by a collagenase-hyaluronidase procedure. Exclusion of trypan blue and respiratory measurements indicate that the cells were functionally intact and metabolically active. The uptakes of phosphate and alpha-methylglucoside were stimulated markedly by Na+ in the extracellular medium. Phosphate uptake in the presence of Na+ was saturable with respect to phosphate concentration; half-maximal activity was obtained with approximately 0.2 mM. Three hours after 1,25-(OH)2D3 was injected into vitamin D-deficient chicks the Na+-dependent phosphate uptake by the isolated cells had increased about 40%, i.e., 2.00 compared with 1.44 nmol.min-1.mg protein-1. Phosphate uptake in the presence of K+ in the extracellular medium and alpha-methylglucoside uptake in the presence or absence of Na+ were unchanged. In a secondary response found 17 h after 1,25-(OH)2D3 injection, Na+-dependent phosphate uptake decreased. Serum concentrations of phosphorus and calcium were not measurably changed in the 3-h repleted bird, but both levels were increased 17 h after treatment. Administration of phosphate into vitamin D-deficient chicks, so that the serum concentration of phosphorus was raised to that of the 17-h 1,25-(OH)2D3 repleted animal, effected a comparable decrease in phosphate uptake. Serum calcium levels were not altered by this treatment. The actions of parathyroid hormone in stimulating adenylate cyclase and in inhibiting phosphate uptake were notably blunted in the vitamin D-deficient chick. Sensitivity to parathyroid hormone was not restored until several days after 1,25-(OH)2D3 repletion. These findings suggest that the initial response to 1,25-(OH)2D3, to increase renal phosphate uptake, and the secondary response, to decrease phosphate uptake, were by parathyroid hormone-independent processes. The results also indicate that the isolated renal cell represents an excellent model for studying the mechanism by which 1,25-(OH)2D3 regulates phosphate transport in the kidney.
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PMID:Effects of 1,25-(OH)2D3 administered in vivo on phosphate uptake by isolated chick renal cells. 689 66

Glucagon-sensitive adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] activity was measured in nine different portions of the rat nephron. Each sample contained a single piece of tubule isolated by microdissection from collagenase-treated kidney tissue. As compared to basal activity, 1 microM porcine glucagon stimulated adenylate cyclase 60-fold in the medullary portion and 40-fold in the cortical portion of the thick ascending limb, 23-fold in the early distal convoluted tubule, 11-rold in the cortical collecting tubule, and 8-fold in the medullary collecting tubule. No stimulation was observed in proximaly tubules and thin segments of the loop of Henle. Half-maximal stimulations were obtained with about 10 nM glucagon in the responsive nephron portions.
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PMID:The distal nephron of rat kidney: a target site for glucagon. 693 29


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