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)

Dispersed cells from the submandibular gland of the male rat were prepared by collagenase treatment to study the mechanism by which immunoreactive tonin is secreted in vitro. Norepinephrine, epinephrine, and phenylephrine stimulated tonin release, an effect that was inhibited by phentolamine but not by propranolol, whereas isoproterenol, carbachol, histamine, and serotonin did not stimulate tonin release. The stimulatory effect elicited by alpha-adrenergic agonists was inhibited by both removal of Ca2+ from the medium and addition of diltiazem and nifedipine, both selective calcium channel blockers. The divalent cation ionophore A23187 stimulated tonin release in the presence of Ca2+, but not in the presence of Mg2+. Dibutyryl cyclic adenosine 3',5'-monophosphate, methylisobutylxanthine, angiotensin II, and vasoactive intestinal peptide had no effect on tonin release. The apparent molecular size of immunoreactive tonin released into the medium under basal and norepinephrine-stimulated conditions was similar to that of standard tonin by gel exclusion chromatography. These data suggest that the in vitro secretion of immunoreactive tonin from rat submandibular gland is initiated by activation of alpha-adrenergic receptors and apparently involves a mechanism dependent not on cyclic adenosine 3',5'-monophosphate, but on the influx of extracellular Ca2+.
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PMID:In vitro secretion of immunoreactive tonin from dispersed rat submandibular gland cells. 301 87

A superfusion technique was adapted to collagenase-dispersed renal medullary and cortical tubular cells to study prostaglandin (PG) synthesis in response to arginine vasopressin (AVP), angiotensin II (ANG II), bradykinin (BK), Ca2+ ionophore A23187, and to changes in osmolality. Medullary and cortical cells promptly responded to the stimuli by an increase in PGE2 and PGF2 alpha production, whereas 6-keto-PGF1 alpha was not detected. AVP and BK were active on medullary cells, and ANG II was active mainly on cortical cells. A23187 stimulated PG synthesis in both cells but predominantly in the medulla. PG synthesis was dependent on the presence of extracellular Ca2+. The Ca2+ entry blocking agents verapamil and lanthanum did not inhibit the PG response to AVP, BK, and ANG II. Thus peptide hormone-stimulated PG synthesis in renal tubular cells did not depend on Ca2+ influx through channels blocked by these agents. Hyperosmolar NaCl or mannitol stimulated PG synthesis in cortical and, more markedly, in medullary cells. Hyperosmolar urea inhibited PGE2 synthesis stimulated by peptide hormones, NaCl, and A23187 in both cell preparations. In conclusion, the superfusion of isolated tubular cells is a useful method to study the dynamic aspects of renal PG release in response to various sequentially applied stimuli.
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PMID:Dynamic response of PG synthesis to peptide hormones and osmolality in renal tubular cells. 308 19

The production of prostaglandins by rat renal tubular cells and by rat vascular smooth muscle cells (VSMC) in response to vasoactive hormones was examined. A superfusion technique was used to stimulate collagenase-dispersed renal cortical or medullary tubular cells and trypsinized rat aortic smooth muscle cells with vasoactive hormones and ANF. All cell types responded promptly to the stimuli in a dose-dependent manner. Renal tubular cells produced mainly PGE2, less PGF2 alpha and no 6-keto-PGF1 alpha, while VSMC produced exclusively 6-keto-PGF1 alpha. This production of PG was strictly dependent on the presence of extracellular Ca2+ and was not inhibited by antagonists of voltage-dependent Ca2+-channels. Angiotensin II (Ang II) was active on cortical tubular cells and VSMC. Sar1-Ala8-angiotensin II blocked this action. Arginine-vasopressin (AVP acted on medullary tubular cells and VSMC and its effect was inhibited by selective V1-antagonists. The V2-agonist dDAVP had no effect on PG production. A clear distinction between V1-receptor mediated PG release and V2-receptor mediated cAMP extrusion was observed in medullary tubular cells. Bradykinin was a weak agonist on medullary tubular cell. The synthetic (1-24) atrial natriuretic peptide did not prevent 6-keto-PGF1 alpha release induced by Ang II or AVP in VSMC nor the PGE2 release in cortical tubular cells induced by Ang II.
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PMID:The regulation of prostaglandins by vasoactive hormones in renal tubular and vascular smooth muscle cells. 312 55

Receptors for angiotensin II (AII) were identified and characterized in testes of rats and several primate species. Autoradiographic analysis of the binding of 125I-labeled [Sar1,Ile8]AII to rat, rhesus monkey, cebus monkey, and human testicular slide-mounted frozen sections indicated specific binding to Leydig cells in the interstitium. In rat collagenase-dispersed interstitial cells fractionated by Percoll gradient, AII receptor content was parallel to that of hCG receptors, confirming that the AII receptors are in the Leydig cells. In rat dispersed Leydig cells, binding was specific for AII and its analogs and of high affinity (Kd, 4.8 nM), with a receptor concentration of 15 fmol/10(6) cells. Studies of AII receptors in rat testes during development reveals the presence of high receptor density in newborn rats which decreases toward the adult age (4934 +/- 309, 1460 +/- 228, 772 +/- 169, and 82 +/- 12 fmol/mg protein at 5, 15, 20, and 30 days of age, respectively) with no change in affinity. At all ages receptors were located in the interstitium, and the decrease in binding was parallel to the decrease in the interstitial to tubular ratio observed with age. AII receptor properties in membrane-rich fractions from prepuberal testes were similar in the rat and rhesus monkey. Binding was time and temperature dependent, reaching a plateau at 60 min at 37 C, and was increased by divalent cations, EGTA, and dithiothreitol up to 0.5 mM. In membranes from prepuberal monkey testes, AII receptors were specific for AII analogs and of high affinity (Kd, 4.2 nM) with a receptor concentration of 7599 +/- 1342 fmol/mg protein. The presence of AII receptors in Leydig cells in rat and primate testes in conjunction with reports of the presence of other components of the renin-angiotensin system in the testes suggests that the peptide has a physiological role in testicular function.
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PMID:Angiotensin II receptors in testes. 335 72

In this study we report on the characterization of a highly enriched population of cultured vascular smooth muscle cells (SMC) prepared from collagenase-treated medial layer explant outgrowths of rabbit aortae. Studies done on cells from first passage explant outgrowths showed that the cells retain the fine structural features of vascular SMC in situ, can be immunostained with anti-smooth muscle myosin IgG, and bind [125I]angiotensin II (ANG II) in a specific and saturable manner with an apparent Kd of 1 nM. Addition of ANG II (0.1 microM) to the cultures causes obvious shape changes and retraction of cell processes. Electron microscopic autoradiography of cells labeled with [125I]ANG II show that the initial site of interaction of ANG II with the SMC is the plasma membrane. The distribution of ANG II receptors among cells in the population was studied using light microscopic autoradiography. The autoradiographical grain density varied among cells in the population ranging from cells that were heavily labeled to those that possessed virtually no label. These data imply that the expression of ANG II receptors may be limited to a certain progeny within the cell population or is a function of their stage within the cell cycle.
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PMID:Interaction of angiotensin II with functional smooth muscle cells in culture. 342 8

The effect of angiotensin II (ANG II) on the secretion of angiotensinogen was studied in isolated rat hepatocytes, obtained by the collagenase perfusion technique and Percoll-density gradient centrifugation, and in the isolated perfused rat liver. In isolated hepatocytes, steady state concentrations of about 1, 10 or 100 nM of ANG II during 90 min of preincubation resulted in a 5, 27 and 33% increase of angiotensinogen secreted during a subsequent 3 hour incubation period. Secretion rates during the last hour of incubation were increased by about 70% by the two higher ANG II concentrations, as compared to controls. Hydrocortisone also induced an increased secretion of angiotensinogen in hepatocytes. The effect of ANG II was prevented by saralasin, a competitive ANG II-antagonist and by actinomycin D. ANG II had no effect of the rate of albumin secretion and of total protein secretion. In the isolated perfused liver, ANG II induced a similar increase of angiotensinogen secretion, without affecting albumin and total protein secretion rates. These observations are consistent with the view that ANG II is participating in a feed back stimulation system of angiotensinogen synthesis and secretion in vivo.
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PMID:Induction of angiotensinogen synthesis and secretion by angiotensin II. 343 79

Isolated hepatocytes were prepared from rat liver by collagenase perfusion and density gradient centrifugation. The hepatocyte preparation released angiotensinogen at a basal rate of 50-120 pmol/g wet weight per h. Release was linear with time for at least 4 h. Angiotensinogen secretion was reduced in the presence of actinomycin D, and inhibited by cycloheximide, puromycin, colchicine and vinblastine. In the presence of tunicamycin, an inhibitor of N-glycosylation, the secretion of angiotensinogen as well as total protein and albumin secretion were diminished. Hepatocytes from nephrectomized rats exhibit an increased secretion rate of angiotensinogen, whereas total protein secretion was unaltered. Preincubation of hepatocytes with hydrocortisone (0.1 mM) or angiotensin II (10 nM) induced an increase of angiotensinogen release. There was no concomitant increase of total protein or albumin secretion, indicating that these effects are not the expression of a general stimulation of protein synthesis and secretion.
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PMID:Hormonal and pharmacological alteration of angiotensinogen secretion from rat hepatocytes. 395 81

The present study determined the effect of [Sar(1)-Ile(8)]-angiotensin II on steroidogenesis and induced aldosterone synthesis by the octapeptide angiotensin II, the heptapeptide des-Asp(1)-angiotensin II, and adrenocorticotropic hormone. Rabbit adrenal cells were suspended by incubation of the capsular cortical tissue with collagenase, and aldosterone levels were determined by immunoassay. Steroidogenic responses to angiotensin II and des-Asp(1)-angiotensin were essentially the same. [Sar(1)-Ile(8)]-angiotensin II (10(-7) to 5 x 10(-7) M) had no significant effect on basal aldosterone biosynthesis. However, when added with steroidogenic peptides, it completely blocked the effect of angiotensin II and des-Asp(1)-angiotensin II but not of adrenocorticotropic hormone. The dose ratio of the antagonist to angiotensin II that gave 100% inhibition was about 2:1 and to des-Asp(1)-angiotensin II, about 50:1. The data suggest that des-Asp(1)-angiotensin II has a much higher affinity for the angiotensin receptor in adrenal cortex than angiotensin II.
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PMID:Inhibition of induced aldosterone biosynthesis with a specific antagonist of angiotensin II. 436 Sep 40

Subcellular fraction and collagenase-dispersed isolated adrenal fasciculata and glomerulosa cells from human and primate adrenal glands and cortisol-producing tumors have been utilized to study angiotensin II (Ang II) receptors and steroid biosynthesis. The receptor density of glomerulosa was threefold higher than that fasciculata. A benign cortisol-producing adenoma did not differ from normal fasciculata, but a malignant tumor had significantly lower affinity binding. Agonist and antagonist analogues of Ang II competed for binding sites commensurate with known biologic activity. The Kd Analogue binding also had corresponding changes in cortisol biosynthesis. The ED50 for aldosterone biosynthesis by glomerulosa cells was significantly lower at 55 pmol/L. Fewer receptors in human fasciculata as compared to glomerulosa and a less sensitive response to Ang II are consistent with previous in vitro observations in other species. These studies suggest that there may be a biologically relevant Ang II receptor of human and primate adrenal fasciculata that share many characteristics with the receptor of the glomerulosa.
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PMID:Angiotensin II receptors of human and primate adrenal fasciculata and glomerulosa: correlations of binding and steroidogenesis. 608 82

The effect of the natrium ionophore, monensin, on aldosterone production was studied using rat adrenal collagenase-dispersed capsular cells. Monensin inhibited aldosterone production in a dose-dependent fashion (10(-9)-10(-6)M). Although monensin inhibited both ACTH- and angiotensin II (AT-II)-stimulated aldosterone production, its inhibitory effect on ACTH-stimulated aldosterone production was greater than that on AT-II-stimulated aldosterone production. The inhibitory effect of monensin on aldosterone production was not accompanied by significant changes in cAMP production. Furthermore, (Bu)2cAMP-stimulated aldosterone production was inhibited by monensin. These results suggest that the inhibitory effect of monensin on aldosterone production is due to an increase in intracellular sodium ion concentration, and that monensin acts at step(s) distal to the generation of cAMP. The differences in the inhibitory effects of monensin on the steroidogenic action of AT-II and that of ACTH may be related to the presence of different steroidogenic mechanisms, including calcium ion dependency.
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PMID:Effect of natrium ionophore on aldosterone production in the rat adrenal gland. 609 48


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