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)

Primary cultures of adult rat liver parenchymal cells, isolated by the collagenase perfusion technique and maintained as a monolayer, were used to investigate the characteristics of hepatic cadmium accumulation and metabolism. Cadmium accumulation was found to be a temperature- and concentration-dependent process that required sulfhydryl groups and was significantly stimulated by the addition of dexamethasone to the medium. Once taken up, cadmium was less available for exit-exchange processes than its biologically required congener, zinc. Moreover, cadmium influx enhanced zinc efflux. While most of the intracellular cadmium was located in the cytosol, its distribution within this fraction was altered with time. Initially the metal was bound to both high molecular weight species (less than 50 000) and metallothionein. As the incubation period increased, the cytosol concentration of cadmium and the percentage of this metal associated with metallothionein was likewise increased. [3H]Amino acid incorporation studies indicated that the accumulation of cadmium resulted in de novo synthesis of the 1 and 2 forms of metallothionein.
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PMID:Cadmium accumulation and metabolism by rat liver parenchymal cells in primary monolayer culture. 42 Aug 70

The effect of cadmium chloride (CdCl2) on cultured human vascular endothelial (HVE) cells and cultured human fibroblasts (HAIN-55 cells) was investigated. Umbilical vein-derived HVE cells were collected by enzymatic digestion with collagenase. At the concentration of 0-10 microM, Cd had hardly any effect on the cell viability of either cells. The viability of HVE cells decreased markedly at 100 microM, but not that of HAIN-55 cells. Morphologic examination by phase contrast microscopy revealed a more damaging effect of Cd on HVE cells than on HAIN-55 cells. These results suggest that Cd is more cytotoxic to HVE cells than HAIN-55 cells.
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PMID:Cadmium injury of cultured human vascular endothelial cells. 181 48

The effects of cadmium and zinc on bone resorption were investigated using fetal mouse calvaria organ culture. Cadmium treatment (0.5 microM) stimulated bone resorption in fetal mouse calvaria via prostaglandin E2 production. Concomitant treatment of zinc with cadmium prevented bone resorption by cadmium in a dose-dependent manner of zinc. The zinc treatment also prevented the stimulation of prostaglandin E2 production by cadmium. ID50 of zinc for bone resorption showed high similarity to that for prostaglandin E2 production (1.2 microM and 1.6 microM, respectively). To simplify the system, we used osteoclast-enriched and osteoblast-enriched cell populations obtained from mice calvariae by collagenase digestion method. Prostaglandin E2 was produced in osteoblast-enriched cell culture more than in osteoclast-enriched cell culture. Cadmium stimulated prostaglandin E2 production in osteoblast-enriched cell culture, but not in osteoclast-enriched cell culture. Zinc also prevented the stimulatory effect of cadmium on prostaglandin E2 production in osteoblast-enriched cell culture. Zinc partially, but significantly, inhibited cadmium-accumulation in both calvaria and osteoblast-enriched cell culture. These results strongly suggest that zinc prevents cadmium-induced prostaglandin E2 production and bone resorption through the interaction between the two metals on osteoblasts involved in the inhibition of cadmium-accumulation.
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PMID:Preventive effect of zinc against cadmium-induced bone resorption. 234 56

Cadmium (Cd)-induced acute testicular toxicity and testicular interstitial cell (IC) tumors can be prevented by low-dose Cd pretreatment. The mechanism of this self-tolerance is unknown. In this regard glutathione (GSH) may play a role in protecting cells from damage by Cd. Therefore, possible mechanisms of self tolerance to Cd in ICs were investigated with emphasis on sulfhydryl metabolism. Rats were pretreated with low-dose Cd (3.0 mumol/kg, sc). Such low-dose Cd pretreatment prevented the necrotizing effects of normally testopathic doses of Cd (20.0 mumol/kg, sc) given 24 hr later. ICs were isolated by collagenase dispersion 24 hr after pretreatment and incubated with Cd (1.0 mM) for 1 hr. In vivo Cd-pretreatment alone increased GSH levels (as determined by HPLC) of whole cells (17%) and cytosol (17%) compared to nonpretreated control. When ICs from nonpretreated rats were exposed to Cd in vitro, GSH in whole cells declined 8% compared to nonpretreated control and 21% compared to cells from in vivo Cd-pretreated rats. In ICs isolated from pretreated rats and exposed to Cd in vitro, GSH levels were normal in whole cells and slightly increased in cytosol. In whole testes low-dose Cd reduced GSH overall, both in cytosol (34%) and in nuclei (14%). Changes in cysteine levels were also seen, similar to those of GSH in whole ICs and cytosol. Neither low-dose in vivo Cd-pretreatment nor in vitro Cd exposure greatly altered levels of the low Mr testicular Cd-binding proteins as assessed by electrophoresis. These results indicate that sulfhydryl metabolism, specifically increased GSH, may be a factor in self tolerance to Cd in ICs.
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PMID:Involvement of sulfhydryl metabolism in tolerance to cadmium in testicular cells. 236 Feb 5

Voltage-clamp experiments were carried out with the objective of identifying and characterizing the time- and voltage-dependent properties of a transient outward current recorded in single myocytes from the crista terminalis region of the rabbit heart. A collagenase enzymic dispersion procedure similar to that described by Desilets & Horackova (1982) was used to obtain these viable individual myocytes. Transmembrane ionic currents were recorded using a single micro-electrode voltage-clamp technique. In experiments aimed at studying a tetrodotoxin-resistant transient inward current, (ICa); a transient outward current was consistently recorded following blockade of ICa with Cd2+ (5 X 10(-4) M). The time and voltage dependence of the activation and inactivation of this current were measured. Its steady-state inactivation curve spans the voltage range -70 to -10 mV, and it is activated between -20 and +10 mV. The reversal potential of this transient outward current is approximately -75 mV in [K+]O 5 mM, suggesting that it is carried mainly by K+. This transient outward current can be inhibited completely by external application of 4-aminopyridine (4-AP, 3 mM). The time- and voltage-dependent properties, the reversal potential, and the sensitivity to 4-AP of this transient outward current are all very similar to those of a transient outward current first identified in molluscan neurones. Hence, we have labelled it, IA. Selective inhibition of IA and knowledge of its voltage- and time-dependent properties yield specific predictions concerning its role in the action potential of isolated crista terminalis cells. Consistent with these predictions, a decrease in stimulus rate is found to decrease the duration of the action potential and vice versa; and application of effective doses of 4-AP results in a substantial lengthening of the action potential. These results are discussed in terms of the possible physiological role of IA in subsidiary or follower pace-maker tissue, and the anatomical and physiological heterogeneity of the sino-atrial node region of the rabbit heart.
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PMID:A transient outward current in isolated cells from the crista terminalis of rabbit heart. 241 13

1. Catecholamines, adenosine, gonadotrophins, vasoactive intestinal peptide (VIP) and E-series prostaglandins all elicit K+ currents in follicle-enclosed Xenopus oocytes. Evidence suggests that cyclic nucleotides act as intracellular messengers in the activation of this K+ conductance. Muscarinic agonists and some divalent cations (e.g. Co2+, Mn2+, Ni2+ and Cd2+) elicit slow oscillatory Cl- currents, which are activated through hydrolysis of inositol phospholipids and mobilization of intracellular calcium by inositol phosphates. 2. We investigated whether these membrane current responses were generated in the oocyte itself or in enveloping follicular cells which are coupled to the oocyte by gap junctions. Oocytes were defolliculated, either enzymatically using collagenase, or by manual dissection combined with rolling over poly-L-lysine-coated slides. Removal of follicular cells was checked using scanning electron microscopy. Membrane current responses of defolliculated oocytes were compared with responses seen in follicle-enclosed oocytes taken from the same ovary. 3. The K+ responses evoked by all the various hormones/neurotransmitters were either drastically reduced (greater than 90%) or abolished by defolliculation. K+ currents generated by the adenylate cyclase activator forskolin and by intraoocyte injection of adenosine 3',5'-cyclic monophosphate (cyclic AMP), or guanosine 3',5'-cyclic monophosphate were similarly reduced in defolliculated oocytes. In contrast, oscillatory Cl- currents to acetylcholine and divalent cations were selectively preserved through defolliculation. 4. Injection of cyclic AMP (1-20 pmol) into defolliculated oocytes had little or no effect on oscillatory Cl- currents elicited by ACh. However, the calcium-dependent transient Cl- current, activated by depolarization of the oocyte membrane, was consistently potentiated (100-900%) by injections of cyclic AMP (1-10 pmol). 5. These experiments suggest that cyclic nucleotide-activated K+ currents arise essentially in follicular cells and are monitored within the oocyte through electrical coupling by gap junctions. Oscillatory Cl- responses evoked by ACh and divalent cations are produced largely or wholly in the oocyte itself.
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PMID:Effects of defolliculation on membrane current responses of Xenopus oocytes. 255 77

Matrix vesicles (MV) isolated from chicken growth plate by collagenase digestion and incubated in 45Ca-labelled synthetic cartilage lymph (SCL) rapidly induce mineral formation. 45Ca uptake occurs in three distinct stages: (1) an initial lag period of limited accumulation, (2) a period of rapid ion uptake and (3) an extended period of slower uptake. Treatment of MV with buffered aqueous 1,10-phenanthroline (OP), a metal ion chelator, eliminated the lag period, promoting immediate, enhanced Ca2+ uptake. Analysis of MV for trace metals showed them to contain relatively high concentrations of Zn (1.58 mumol/g MV) and lesser amounts of Cu (0.07 mumol/g MV). At least 30-40% of the Zn was readily extractable in isosmotic buffers. Addition of Zn to SCL at levels as low as 5 microM completely inhibited MV mineralization; addition of OP to Zn-inhibited MV restored their ability to mineralize. The findings suggest that Zn2+ ions act as an endogenous regulator of MV Ca2+ uptake and that the normal lag period results from a competition between Zn2+ and Ca2+ for high affinity Ca2+ binding sites in the MV membrane or within the MV lumen. Other metals tested included Cu2+, Pb2+ and Cd2+ which had little or no effect on MV mineralization, Mn2+, which had an intermediate effect, and Al3+, which was found to be almost as inhibitory as Zn2+. This finding may have implications for aluminum-associated osteomalacia.
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PMID:Regulatory effect of endogenous zinc and inhibitory action of toxic metal ions on calcium accumulation by matrix vesicles in vitro. 261 45

Cadmium (Cd) induces testicular tumors of interstitial cell (IC) origin in rats which can be prevented by zinc (Zn). Zn-induced synthesis of metallothionein (MT), a metal-binding protein with a high affinity for Cd, is thought to account for tolerance to Cd in most tissues by sequestration of Cd. However, the mechanism of Zn inhibition of Cd-induced carcinogenesis in the testes is unknown. Our studies with ICs obtained by collagenase dispersion of rat testes, indicate the levels of the Cd-binding protein in ICs are unaltered by Zn. This testicular protein also was found to differ from MT in amino acid content and to have a lower affinity for Cd. Thus, MT does not seem to be involved in protection of ICs against Cd carcinogenesis. Altered Cd toxicokinetics as a possible explanation for Zn-induced tolerance was therefore explored. Cd uptake into isolated ICs had passive diffusion and nonpassive (carrier mediated or active transport or both) components. The nonpassive component of Cd accumulation was markedly reduced by addition of Zn in vitro, indicative of competition for uptake at the cellular level. These results indicate that toxicokinetic alterations leading to reduced Cd accumulation may play an important role in Zn induction of tolerance to Cd carcinogenesis in the testes.
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PMID:In vitro assessment of target cell specificity in cadmium carcinogenesis: interactions of cadmium and zinc with isolated interstitial cells of the rat testes. 339 32

Previous studies have shown that the administration of cadmium causes extensive necrosis of the testes and, eventually, a high incidence of interstitial cell tumors. However, the interactions of cadmium with interstitial cells of the testes have not been well defined. Therefore, this study was designed to assess the uptake of cadmium into this potential target cell of cadmium carcinogenesis. Interstitial cells were prepared by collagenase dispersion of decapsulated Wistar rat testes and separated from seminiferous tubules by unit gravity sedimentation. Such preparations showed a high exclusion rate of trypan blue. The interstitial cell preparations were incubated at 33 degrees with various concentrations of cadmium (1.0 to 100 microM) for periods ranging from 0.5 to 60 min. At the end of the incubation, cellular cadmium was separated from cadmium in the media by centrifugation through an oil layer. Initial experiments showed three distinct phases of cadmium influx into interstitial cells, a primary rapid velocity phase (V0; 0 to 1.5 min), a second intermediate velocity phase (V1; 3 to 12 min), and a third low velocity phase (V2; 15 to 60 min). V2 appeared to have both influx and efflux components, as efflux experiments indicated an approximate 20% loss of cadmium from 15 to 60 min. The initial phase was found to be nonsaturable and was not decreased by inclusion of potassium cyanide (1.0 mM), N-ethylmaleimide (1.0 mM), or zinc (100 microM) in the incubation mixture. However, V1 was found to be saturable between 50 and 100 microM cadmium and was substantially decreased by the inclusion of potassium cyanide, N-ethylmaleimide or zinc during incubation. These data suggest that cadmium is taken up into interstitial cells by a transport system that may normally function in zinc uptake and may possibly constitute carrier mediated or active transport.
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PMID:Interactions of cadmium with interstitial tissue of the rat testes. Uptake of cadmium by isolated interstitial cells. 401 91

The metabolism of cadmium was investigated in Wistar-rat liver non-parenchymal cells. Kupffer and endothelial cells, the major cell populations lining the sinusoidal tracts, were isolated by collagenase dispersion and purified by centrifugal elutriation. At 20 h after subcutaneous injection of the metal salt (1.5 mg of Cd/kg body weight), endothelial cells accumulated 2-fold higher concentrations of Cd than did Kupffer or parenchymal cells. Most of the Cd in non-parenchymal cells was associated with cytosolic metallothionein (MT), the low-Mr heavy-metal-binding protein(s). When MT was quantified in cytosols from cells isolated from control rats by a 203Hg competitive-binding assay, low levels were found to be present in Kupffer, endothelial and parenchymal cells. Cd injection significantly increased MT levels in all three cell types. The induction of MT synthesis was investigated in vitro by using primary monolayer cultures. The incorporation of [35S]cysteine into MT increased 47% over constitutive levels in endothelial-cell cultures after the addition of 0.8 microM-Cd2+ to the medium for 10 h. MT synthesis in Kupffer cells was not observed. The lack of MT synthesis by monolayer cultures of Kupffer cells in vitro was associated with a decreased capacity of these cells to accumulate heavy metals from the extracellular medium. This apparent decreased ability to transport metals did not reflect a general defect in either cellular function or metabolic activity, since isolated Kupffer cells incorporated [3H]leucine into protein at rates comparable with those shown by liver parenchymal cells and readily phagocytosed particles.
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PMID:Cadmium metabolism by rat liver endothelial and Kupffer cells. 647 90


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