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 stimulation of aldosterone secretion from adrenal glomerulosa cells by angiotensin II (AII), potassium, and ACTH is highly dependent on the extracellular calcium concentration. To evaluate the role of voltage-dependent calcium channels in aldosterone production, we analyzed the actions and binding of calcium channel antagonists in collagenase-dispersed adrenal glomerulosa cells and membrane-rich particles. In rat glomerulosa cells, nifedipine caused dose-dependent inhibition of the aldosterone responses to AII and potassium, with half-maximum inhibitory concentration (IC50) of 100 nM, but had no effect on ACTH or 8-bromo-cAMP stimulated steroidogenesis in adrenal glomerulosa and fasciculata cells. Binding studies with [3H]nitrendipine in adrenal glomerulosa cells revealed a high affinity site with dissociation constant (Kd) of 0.4 +/- 0.1 nM, similar to that described in other tissues but about 100-fold lower than the IC50 for blockade of aldosterone production. However, Scatchard analysis of binding data from three of seven experiments in isolated adrenal glomerulosa cells revealed a low affinity site with Kd of 130 nM, in agreement with the IC50 for the effect of nifedipine on aldosterone production. In rat adrenal particles, nitrendipine-binding sites were located in the adrenal capsule and medulla and were undetectable in the zona fasciculata. Furthermore, there was a close correlation (r = 0.92) between the concentrations of nitrendipine-binding sites and AII receptors in the different zones of the adrenal in rat, dog, and cow, suggesting a functional relationship between AII receptors and calcium channels. These studies have shown a major and selective role of voltage-dependent calcium channels in the control of aldosterone secretion by the major physiological regulators, AII and potassium.
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PMID:Participation of voltage-dependent calcium channels in the regulation of adrenal glomerulosa function by angiotensin II and potassium. 241 49

To study the properties of vascular smooth muscle in hypertension without the influence of the nerves and endothelium, a procedure was developed to isolate single smooth muscle cells from tail arteries of spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) normotensive control rats. Perfusion of intact arteries with a solution of papain and collagenase produced dense populations of viable cells (more than 10(4) cells/ml) that remained relaxed in the presence of physiological levels of calcium. Contractile responses of smooth muscle cells from the SHR were significantly more sensitive to noradrenaline, potassium depolarization, and the calcium channel agonist Bay K 8644 compared with those from WKY rats. Enhanced sensitivity to calcium in the SHR was also observed on readdition of calcium to cells preincubated in noradrenaline or KCl in a calcium-free medium. These results provide evidence for alterations in the properties of vascular smooth muscle in the SHR at the single cell level.
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PMID:Isolation and characterization of single vascular smooth muscle cells from spontaneously hypertensive rats. 247 94

Recent data have implicated the phosphatidylinositol/calcium second-messenger system in the control of aldosterone secretion by the adrenal zona glomerulosa. However, in the rat adrenal there are few reports of a direct effect of protein kinase C activation on steroid secretion, while the effects of calcium mobilization may be variable. Since the rat adrenal zona glomerulosa is sensitive to the mode of tissue preparation, these mechanisms were reinvestigated in intact (non-dispersed) capsular tissue and collagenase-dispersed zona glomerulosa cells. Steroidogenesis in the intact zona glomerulosa was markedly affected by agonists of the calcium messenger system. Most notably, aldosterone and 18-hydroxycorticosterone (18-OH-B) secretion were stimulated by A23187 (100 nmol to 10 mumols/l) and BAY K 8644 (500 nmol/l). Phorbol 12-myristate 13-acetate (TPA; 1 pmol to 1 mumol/l) stimulated aldosterone secretion at all doses and caused a dose-dependent increase in 18-OH-B and 18-hydroxydeoxycorticosterone (18-OH-DOC) secretion. Corticosterone secretion was slightly increased in the presence of A23187 but not by TPA or BAY K 8644. Production of 18-OH-DOC was unaffected by A23187 and BAY K 8644. The calcium channel antagonist verapamil (10 mumols/l) inhibited ACTH-stimulated aldosterone secretion by the intact zona glomerulosa but had no effect on corticosterone secretion. Verapamil (10 mumols/l) also inhibited the increase in aldosterone secretion by collagenase-dispersed zona glomerulosa cells stimulated by ACTH (100 fmol to 100 nmol/l), angiotensin II (100 pmol to 10 nmol/l) and potassium (5.9 and 8.4 mmol/l); stimulated corticosterone secretion was unaffected.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Specific effects of agonists of the calcium messenger system on secretion of 'late-pathway' steroid products by intact tissue and dispersed cells of the rat adrenal zona glomerulosa. 247 55

We previously reported that thyrotropin-releasing hormone (TRH) and human pancreatic growth hormone-releasing factor (hpGRF) exert synergistic (greater than additive) effects on growth hormone (GH) release from chicken pituitary cells in primary culture. In the present studies the possible participation of calcium in GH release and in TRH and hpGRF synergy was investigated. Following dispersion with collagenase, cells were cultured for 48 hr prior to exposure (2 hr) to test agents. Cultured cells were exposed to a range of calcium concentrations (0, 0.02, 0.2, and 2.0 mM) in the presence and absence of secretagogues. These results demonstrated that basal GH release was not altered by the concentration of calcium in the medium: however, secretagogue-induced GH release required calcium. Thus, TRH, hpGRF, 8 Br-cAMP, or forskolin stimulated GH release in the absence of calcium. Furthermore, synergistic GH release evoked by TRH and hpGRF, 8 Br-cAMP, or forskolin was observed only at the highest calcium concentration (2.0 mM). In other studies, ionomycin (10(-5) M), a calcium ionophore, stimulated GH release to a value about 125% over the basal (absence of test agent) value. Ionomycin-induced GH release was not affected by TRH (5.0 ng/ml); the combined effects of ionomycin (10(-7)-10(-5) M) and hpGRF (5.0 ng/ml) on GH release were less than additive. However, ionomycin (10(-5) M) further increased GH release over that resulting from the synergistic action of TRH and hpGRF (5.0 ng/ml each). Verapamil (a calcium channel blocker) did not affect GH release induced by either TRH or hpGRF (5.0 ng/ml each). However, this agent did inhibit synergistic GH release evoked by TRH and hpGRF, 8 Br-cAMP, forskolin, or isobutylmethylxanthine. These results suggest that calcium participates in secretagogue-induced GH release from chicken somatotrophs in vitro.
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PMID:Possible participation of calcium in growth hormone release and in thyrotropin-releasing hormone and human pancreatic growth hormone-releasing factor synergy in a primary culture of chicken pituitary cells. 250 91

Surgical morbidity is dictated directly by wound healing. We have studied the effects of elevated calcium levels using cultured keratinocytes in vitro on two of the rate-limiting steps of wound healing, chemotaxis (directed migration) and adhesion. We found that the increased calcium (10 mmol/L) significantly inhibited both keratinocyte chemotaxis and adhesion (p less than 0.05). The calcium effect on adhesion could be partially reversed by pretreatment with the calcium channel blocker verapamil. Based on these data, an animal model was formulated in which topical calcium (5 mmol/L/day) was added to linear incision wounds. This resulted in significantly (p less than 0.05) delayed wound contraction characteristic of a chronic or impaired wound. Wound contraction depends on the presence of fibroblasts that synthesize collagen. The chronic wound was characterized by increased collagenase activity (p less than 0.05) but little alteration in collagen I synthesis. The addition of verapamil to these chronic wounds resulted in improved wound closure. These studies define the molecular and cellular events occurring as a result of the addition of elevated levels of calcium both in vitro and in vivo. Calcium may play a key role in the pathogenesis of chronic wounds.
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PMID:Increased calcium levels alter cellular and molecular events in wound healing. 255 28

Macrophages and monocytes secrete a factor(s) which can stimulate the synthesis of collagenase in synovial cells and in chondrocytes. Incubation of rabbit chondrocytes with macrophage conditioned medium (MCM) and with the calcium channel blockers, nifedipine, verapamil or diltiazem (up to 200 microM) had no effect on collagenase synthesis. However, TMB-8 (8-[N,N-diethylamino]-octyl 3,4,5-trimethoxybenzoate hydrochloride), an inhibitor of internal calcium movement, did inhibit the process with an IC50 of approximately 130 microM. The calmodulin antagonists, trifluoperazine, chlorpromazine and calmidazolium (R-24571) were effective inhibitors of the process with IC50's of 40 microM, 18 microM and 3.5 microM, respectively. Collagenase activity itself was not affected by these agents. The data suggests that calmodulin and/or internal calcium movement may play a role in the macrophage factor-stimulated synthesis of collagenase in rabbit chondrocytes.
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PMID:The effect of calcium channel blockers and calmodulin inhibitors on the macrophage factor-stimulated synthesis of collagenase by rabbit chondrocytes. 284 10

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

Corpora lutea from cyclic ewes were dissociated by collagenase and trypsin/EGTA treatments, and enriched fractions of small and large luteal cells were prepared on gradients of Ficoll. These fractions were incubated separately or remixed before incubation. Colchicine, cytochalasin B and the calcium channel-blocker verapamil significantly reduced progesterone production by both small and large luteal cell fractions, while isoprenaline stimulated an increase in progesterone production by large luteal cell fractions only. When fractions of small and large luteal cells were remixed, no more and no less progesterone was produced than would have been predicted from equivalent fractions incubated separately. There was therefore no evidence of synergism between small and large luteal cells in the production of progesterone. Prostaglandin F-2 alpha, which can inhibit LH-stimulated progesterone production by ovine luteal tissue in vitro, had no effect on LH-stimulated progesterone production by small luteal cell fractions, but significantly inhibited that by enriched fractions of large luteal cells. Since large luteal cell fractions were contaminated with small luteal cells, which are probably responsible for the progesterone-secretory response of these fractions to LH, it was concluded that the inhibition of LH-stimulated progesterone production by small luteal cells is dependent on the presence of large luteal cells. Oxytocin added to large and small luteal cell fractions did not affect progesterone production by either fraction. It was therefore concluded that the inhibitory action of PGF-2 alpha on LH-stimulated progesterone production may require the interaction of large and small luteal cells, but that oxytocin is not likely to be an intermediary in this interaction.
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PMID:Do small and large luteal cells of the sheep interact in the production of progesterone? 386 69

We have developed a new short term in vitro system to examine hypothalamic somatostatin (SRIF) release. Hypothalamic cells were obtained from normal rats after trypsin or collagenase aided dispersion and released immuno-reactive (IR) SRIF which eluted in 3 molecular weight (MW) forms on gel chromatography. The smallest MW form, which constituted the major peak, co-eluted with synthetic cyclic 1-14 SRIF on gel and reverse phase high pressure liquid chromatography (HPLC). After 24 h in culture in medium containing heat inactivated fetal calf serum, cell viability was demonstrated by two techniques, (1) vital staining with trypan blue, and (2) incorporation of 32Pi into phospholipids. SRIF release was also studied at this time which was optimal in terms of responsivity of the cells to depolarizing stimuli. SRIF release increased in a time dependent manner, over 3 h. Membrane depolarization, induced either by potassium chloride 56 mM or ouabain (the Na+, K+-ATPase inhibitor) 10(-6) M or greater, markedly stimulated SRIF release. Incubation at 4 degrees C, or in the presence of EDTA 0.05 M or verapamil, the calcium channel blocker, 50 microM abolished these stimulatory effects. Glucose deprivation was induced by the addition of 2-deoxy-D-glucose (2-DG) to the experimental medium. 2-DG, at concentrations of up to 200 mg%, had no significant effect on SRIF release during incubation periods of up to 1 h.
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PMID:Somatostatin release from dispersed hypothalamic cells - effects of membrane depolarization, calcium and glucose deprivation. 613 93

The physiologic regulation of aldosterone secretion is dependent on extracellular calcium and appears to be mediated by increases in cytosolic free calcium concentration in the zona glomerulosa cell. A specific role for voltage-dependent calcium channels was suggested by previous studies with the calcium channel antagonist verapamil. We therefore studied the [3H]nitrendipine calcium channel binding site in adrenal capsules. These studies revealed a single class of saturable, high affinity sites with KD = .26 +/- .04 nM and Bmax = 105 +/- 5.7 fmol/mg protein. Specific binding of [3H]nitrendipine was inhibited by calcium channel antagonists with potencies nitrendipine = nifedipine much greater than verapamil, while diltiazem had no inhibitory effect. In the rat, binding sites for [3H]nitrendipine were located in the adrenal capsule and medulla and were undetectable in the zona fasciculata. Physiologic studies with collagenase-dispersed adrenal glomerulosa cells demonstrated that nifedipine selectively inhibited angiotensin-II and potassium-stimulated steroidogenesis. These observations suggest both a pharmacologic and physiologic role for the nitrendipine binding site in aldosterone production.
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PMID:[3H]nitrendipine binding to adrenal capsular membranes. 648 81


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