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:3.4.24.3 (collagenase)
18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The production of aldosterone by isolated canine zona glomerulosa cells was measured after the incubation of cell suspensions with angiotensin II and ACTH, and during changes in extracellular potassium concentration. Adrenal cell suspensions were prepared by collagenase digestion and physical dispersion of the capsular layer of the dog adrenal cortex, and aldosterone production was determined by direct radioimmunoassay of cell incubation media. The isolated dog adrenal cells were highly responsive to angiotensin II, with aldosterone production significantly stimulated by concentrations of the octapeptide as low as 10(-11)M. Thus, the steroidogenic response of zona glomerulosa cells was consistently observed at peptide concentrations within the physiological range of angiotensin II in dog plasma, i.e., 2.0-5.0 X 5.0 X 10(-11)M. The maximum aldosterone response of 3-8 times the basal level of steroid production was induced by 3 X 10(-10)M angiotensin II, and a decrease in aldosterone production occurred at peptide concentrations above 10(-9)M. The aldosterone response of isolated adrenal cells to ACTH was consistently less sensitive than their response to angiotensin II, by a factor of 10-20 fold. Aldosterone production was significantly increased by 10(-10)M ACTH, and reached a maximum at 10(-8)M ACTH. By contrast with angiotensin II, ACTH usually evoked a higher maximal level of aldosterone production, and did not produce a decline in steroidogenesis at peptide concentrations above the level which caused maximum stimulation of aldosterone formation. Changes in the potassium concentration of cell incubation media were also accompanied by marked effects upon aldosterone synthesis which was abolished in the absence of potassium and became detectable in the presence of 0.5 mM K+. After remaining constant between 2.5 and 4.0 mM K+, aldosterone production rose sharply above 4.5 mM K+ and reached a maximum at 8 mM K+. These observations provide direct evidence that aldosterone production by zona glomerulosa cells is influenced by changes in angiotensin II levels within the normal plasma range.
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PMID:Aldosterone production by isolated adrenal glomerulosa cells: stimulation by physiological concentrations of angiotensin II. 17 29

The binding properties of the angiotensin II receptors of the adrenal cortex have been studied in isolated cells prepared by collagenase dispersion of the zona glomerulosa of the canine adrenal gland. Such cell preparations are responsive to physiological concentrations of angiotensin II, and permit correlation of binding of angiotensin II and its analogues with aldosterone production in vitro. Uptake of 125I-angiotensin II (5 X 10(-11) M) by glomerulosa cells at 37 degrees C reached a steady state at 45 minutes, with a subsequent plateau for at least 60 minutes. Angiotensin II binding was also dependent upon the hormone and cell concentrations employed during uptake studies. Bound angiotensin II was rapidly dissociated from canine adrenal cells after addition of the unlabeled octapeptide. High affinity sites with equilibrium association constant (Ka) of 3.3 X 10(9) M-1 comprised 25-33% of the receptor population and the remainder of the sites were of lower affinity, 2.5 X 10(8)M-1. Binding of angiotensin II analogues and antagonists was found to be consistent with their biological activities. The analogue most extensively evaluated was [Sar-1]angiotensin II, which exhibited enhanced binding activity when compared to angiotensin II, and had a higher equilibrium association constant by kinetic analysis and direct binding studies. Direct binding of labeled angiotensin II to the adrenal glomerulosa receptor has been correlated with a progressive response in aldosterone production. The steroidogenic response to angiotensin II was maximal when 25% of the receptor population was occupied; this fraction corresponds to the proportion of high affinity receptor sites measured by binding analysis. In addition, inhibition of angiotensin II binding to receptor sites by the competitive antagonist [Sar-1, Ala-8]angiotensin II has been correlated with inhibition of aldosterone production. These findings serve to demonstrate the biological significance of the angiotensin II binding sites of the adrenal cortex, and confirm their role as receptors which mediate the steroidogenic responses to angiotensin II.
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PMID:Receptor binding of angiotensin II and antagonists. Correlation with aldosterone production by isolated canine adrenal glomerulosa cells. 17 62

Amphibian epithelia specialized in trans-cellular sodium transport lose their capacity to react to insulin by a stimulation of this process upon treatment with collagenase; baseline activity and responsiveness to other hormones (vasopressin, aldosterone) bringing about such a stimulation are preserved. This renders it likely that proteases contaminating most collagenase preparations exert a detrimental effect on the receptors held responsible for interaction between insulin and its target cells in the tissues examined.
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PMID:Disappearance of insulin response after enzymatic treatment of sodium-transporting amphibian epithelia. 18 80

Specific receptors for angiotensin II (A II) were demonstrated in membrane fractions and collagenase-dispersed cells from the zona glomerulosa of the rat adrenal gland. The equilibrium association constant (Ka) of the A II binding sites was similar in particulate fractions (2.0 +/- 0.4 (SE) X 10(9) M-1) and intact glomerulosa cells (1.8 +/- 0.3 X 10(9) M-1). Specific binding of [125I]iodo-A II was enhanced by increasing sodium concentration, and in the presence of dithiothreitol, EDTA, and EGTA. Plasma membrane fractions prepared by density gradient centrifugation showed increased binding of [125I]iodo-A II, and were correspondingly enriched in adenylate cyclase and sodium-potassium-dependent ATPase. Steroid production by collagenase-dispersed adrenal glomerulosa cells was highly responsive to A II and ACTH. Significant increases in aldosterone and corticosterone production were elicited by A II concentrations as low as 3 X 10(-11) M, equivalent to normal blood levels of A II in rats (5 X 10(-11) M). The maximum increase in aldosterone production, of 6--7 times the basal value, was obtained at 10(-9) M A II. Dispersed capsular cells were also highly sensitive to ACTH, responding to concentrations down to 3 X 10(-12) M with increased aldosterone production, reaching a maximum aldosterone response of 20-fold above the basal value. The magnitudes of the aldosterone and corticosterone responses to A II in capsular and fasciculata-reticularis cells were commensurate with the distribution of A II receptors, which were 11-fold more concentrated in capsular cells. The ability of A II to evoke aldosterone production at physiological concentrations, and the correspondence between A II binding and steroidogenesis in capsular cells, demonstrate the functional importance of A II receptor sites in the zona glomerulosa of the rat adrenal cortex.
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PMID:Angiotensin II receptors and aldosterone production in rat adrenal glomerulosa cells. 21 98

A method of preparing a suspension of cells of the zona glomerulosa from rat adrenal capsules treated with crude collagenase is described. The cells responded to ACTH, angiotensin II and serotonin by increased production of aldosterone. Pooled human sera or individual human sera (from healthy normal or non-psychiatric in-patients) to a final concentration of 30% had no effect on ACTH-stimulated production of aldosterone. Many serum samples from five patients with manic-depressive psychosis, however, caused a reduction in aldosterone production; 65% of those samples taken during depression, 44% of the samples taken during manic episodes and 23% of the samples taken when the mood was normal. Sera from manic-depressive patients also reduced the production of aldosterone caused by angiotensin II or serotonin. This effect of serum from manic-depressives in vitro may be related to the abnormalities of aldosterone control in such patients.
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PMID:Inhibition of aldosterone production in adrenal cell suspensions by serum from patients with manic-depressive psychosis. 21 27

The role of cyclic AMP in the regulation of aldosterone production by adrenocorticotropic hormone (ACTH), angiotensin II (A II), potassium, and serotonin was examined in collagenase-dispersed adrenal glomerulosa cells. The ability of 8-bromo cyclic AMP and choleragen to stimulate maximum aldosterone production indicated that cyclic AMP could act as second messenger for certain of the aldosterone-stimulating factors. The actions of ACTH and choleragen on aldosterone and cyclic AMP production were correlated in dog and rat cells, and a similar relation was seen during stimulation of rat cells by serotonin. In contrast, A II and potassium did not cause changes in cyclic AMP formation while stimulating aldosterone production. Intracellular and receptor-bound cyclic AMP were increased 3-fold by 10(-7) M ACTH but not by A II. Addition of a phosphodiesterase inhibitor increased the magnitude of the cyclic AMP response to ACTH but did not change the lack of stimulation by A II or potassium. In dog cells, the effects of A II and potassium on aldosterone production were partially additive to those of ACTH, choleragen, and 8-bromo cyclic AMP. In contrast, no additivity was observed between A II and potassium, or between combinations of the cyclic AMP-dependent stimuli. These results indicate that the actions of ACTH on aldosterone secretion are mediated by cyclic AMP formation, whereas A II and potassium stimulate aldosterone production through an independent mechanism. The lack of additivity between steroid responses to A II and potassium suggests that these factors could share a common mode of action on steroidogenesis in zona glomerulosa cells.
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PMID:The role of cyclic AMP in aldosterone production by isolated zona glomerulosa cells. 22 59

A comparison of the receptor binding properties and in vitro metabolism of angiotensin II and [des-Asp1]-angiotensin II was performed in collagenase-dispersed glomerulosa cells from dog adrenal glands. Each peptide was bound rapidly and reversibly to isolated glomerulosa cells, with similar equilibrium and kinetic constants of association and dissociation. The labeled peptide that was bound to glomerulosa cells after incubation with 125I- and 3H-angiotensin II at 37C for 30-60 minutes was predominantly angiotensin II, with about 15% [des-Asp1]-angiotensin II. These findings demonstrate that local formation of the heptapeptide is not an obligatory step in the action of angiotensin II on aldosterone production in the canine adrenals.
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PMID:Formation of DES-ASP1-angiotensin II is not an obligatory step in the steroidogenic action of angiotensin II in the canine adrenal. 74 59

Although adipose tissue appears to be a target organ for glucocorticoid hormones, previous studies have failed to detect glucocorticoid receptors in this tissue. In the present study, the addition of thioglycerol and trasylol to the homogenization medium provided an enuironment in which receptors were successfully demonstrated. [3H]Dexamethasone binding studies were carried out at 0 C in cytosol from various adipose tissues of adrenalectomized rats and bound hormone was separated from free by Sephadex chromtography. Despite the presence of protein protective agents, receptor binding decayed significantly over 24 h but appeared stable from 1 to 5 h. Epididymal fat pad cytosol had an apparent Kdiss at 0 C for dexamethasone of approximately 6 nM and a binding capacity of approximately 200 fmol per mg protein. To prove that the receptors were located in fat cells and not in surrounding connective tissue, isolated adipocytes were prepared by collagenase digestion and receptors were demonstrable in the cytosol from these cells as well. The affinity of series of steroids for the receptor was in the sequence: dexamethasone greater than corticosterone greater than progesterone greater than aldosterone greater than cortexolone greater than testosterone greater than estradiol. Receptors of roughly the same affinity but somewhat fewer binding sites on the basis of cytosol protein were also found on other fat depots including peri-renal, peri-scrotal and popliteal. Of interest is the fact that interscapular brown fat and human subcutaneous fat also possessed similar these receptors, the higher competitive capacity of dexamethasone indicated that the binding was to glucorticoid rather than mineralocorticoid receptors. The data suggest that fat cells contain glucocorticoid receptors which are similar to those seen in other glucocorticoid targets. Presumably these receptors mediate the effects of glucorticoids on adipose tissue.
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PMID:Glucocorticoid receptors in adipose tissue. 83 31

Addition of estradiol-17beta in vitro to suspensions of isolated endometrial cells resulted in significant effects on glucose, water and electrolyte metabolism. Cells were prepared from uterine tissues of ovariectomized rats. In part, the procedures involved incubation with collagenase in Ca2+-, Mg2+-free, phosphate-buffered mammalian Ringer's solution, followed by restoration of divalent cations before gentle scraping of the endometrium from the underlying smoothmuscle. Cells were then disaggregated, washed, separated from coarse and fine debris, and incubated in an enriched medium for 2 h before the start of all experiments. Cellular integrity was established by measurement of electrolyte contents and by dye exclusion methods. Substantial production of 14CO2 from glucose-U-14C by the cell suspensions provided further evidence of cell viability. Estradiol-17beta, 10-9M, elicited significant increments in sodium and water contents within 2 h. Addition of estradiol-17beta, but not the alpha-epimer, also resulted in a significant increase in the yield of 14CO2 as early as 1.5 h, peaking at 2 h. The responses were dose-dependent between 10-10M through 10-8M. The stimulatory effect of estradiol-17beta at 10-9M was abolished in the presence of 3 times 10-6M cortisol or by cellular homogenization. Epithelial cells isolated from rat urinary bladder responded significantly to 6 times 10-9M aldosterone but not to estradiol-17beta, demonstrating specificity of the target site. These data lend further support to the suggestion that a primary action of estrogen in its target cell involves specific changes in the ionic and biochemical profile of the cytoplasm which may ultimately be communicated to the nucleus.
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PMID:Steroid hormone-responsive, isolated endometrial cells. 112 Apr 83

The expression of a novel regenerating (reg) gene has been reported previously in the regenerating islets of a surgical model of diabetes in rats. We exposed collagenase-isolated rat islets for three days to nutrient and non-nutrient growth factors in minimally supplemented RPMI medium (2.7 mmol/l glucose, 2% fetal calf serum), and investigated the relationship between reg gene expression and islet cell replication. RNA was prepared from half of the islets by homogenisation in guanidinium isothiocyanate followed by phenol/chloroform extraction. Northern/dot blot analyses were used to semi-quantify reg mRNA. Islet cell replication was estimated by culturing the remaining islets in radiolabelled thymidine to determine de novo DNA synthesis. Thymidine uptake was stimulated by the following factors: 11 mmol/l glucose (50% increase); 10% amino acids (126% increase); 10% fetal calf serum (39% increase); 100 ng/ml insulin (45% increase); 250 ng/ml growth hormone (65% increase); 1.5 nmol/l aldosterone (29% increase); 2 U/ml platelet derived growth factor (116% increase). The results are expressed as a percentage of the thymidine incorporated into control islets cultured in minimal RPMI (1118 +/- 100 (SD) cpm/microgram protein, n = 15). Increased islet cell replication was paralleled in each case by a clear rise in reg mRNA expression compared to controls. Furthermore, the rank order for reg gene expression was the same as that for thymidine uptake (r = 0.90). The present findings suggest a clear association between reg gene expression and islet cell replication in vitro, and are the first to demonstrate reg gene expression in response to individual growth factors.
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PMID:Expression of an islet regenerating (reg) gene in isolated rat islets: effects of nutrient and non-nutrient growth factors. 137 94


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