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 cholinergic sensitivity of rat diaphragm muscle, me-sured as the magnitude of depolarization responses to repetitive, iontophoretic pulses of acetylcholine (ACh) onto neuromuscular endplates, is increased by addition of ATP to the perfusion medium. Depolarization responses begin to increase within the first min after addition of 10 mM ATP and plateau at 60% above control levels (mean value) after 4 to 6 min. Neither the magnitude nor the time course of the potentiations corresponds to changes in resting potential or membrane resistance. Other nucleotides are equally or less effective at the same concentration: ATP=ADP greater than UTP greater than AMP=GTP (=no added nucleotide control) The duration of the individual ACh responses does not increase during continuous exposure to the active nucleotides for up to 15 min except when the muscle is pretreated with eserine. Mild enzymatic predigestion of the muscle with collagenase and then protease, increasing the availability of the postjunctional membrane to bath-applied drugs, decreases the variability and increases the magnitude of the potentiation to a given dose of ATP. The dose-response curve for ATP is then more than half-maximal at 1 mM and the ranking of the other nucleotides relative to ATP is the same as without predigestion. There is an optimum Ca++ concentration for the potentiation between zero and 2 mM: potentiation is enhanced in Ca++ -free medium, partially blocked in twice-normal Ca++ medium, and totally blocked in Ca++ -free medium 10 min after a 5 min exposure to 2.5 mM EGTA. The similar Ca++ dependence of ACh receptor activation in the absence of added nucleotide suggests that ATP directly facilitates receptor activation by ACh. This facilitory action could be one of the physiological roles for the ATP released from stimulated phrenic nerve.
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PMID:Potentiation of postjunctional cholinergic sensitivity of rat diaphragm muscle by high-energy-phosphate adenine nucleotides. 18 89

The mechanism by which serum stimulates collagen production by fibroblasts was examined. Fibroblasts were exposed to various concentrations of serum and collagen production and mRNA levels were measured. Collagen production was determined as collagenase digestible radioactivity and collagen mRNA levels were measured using a [35S]UTP-labelled pro alpha 1[I] probe. The results showed that increased collagen production correlated with enhanced mRNA levels. Extra- and intracellular collagen degradation was similar in control and serum treated cultures, and "G1" and "S" phase fibroblasts contained similar levels of collagen mRNA. We conclude that serum regulation of collagen synthesis occurs primarily at the transcriptional level and that activation of collagen synthesis is not coupled to mitogenic stimulation.
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PMID:Serum regulation of collagen biosynthesis in human diploid fibroblasts. 359 61

ATP pyrophosphohydrolase was partially purified from fetal bovine epiphyseal cartilage. The purification was about 10- and 100-fold over the enzyme activities of matrix vesicle fraction and cell homogenate, respectively. The pyrophosphohydrolase and alkaline phosphatase were separated by a sequential application of Sepharose CL-6B and DEAE-cellulose column chromatographies. The purified enzyme migrated as a single band corresponding to the molecular weight of 230,000 in sodium dodecyl sulfate-polyacrylamide disc gel by electrophoresis. The enzyme absolutely required Zn2+ for its activity and appeared to bind Zn2+ strongly with an apparent affinity of p[Zn2+]0.5 = 13.4. The apparent Km for ATP was 0.18 mM. The enzyme was also reactive toward various nucleoside triphosphates including GTP, CTP, and UTP. In contrast, various phosphodiesters including RNA, UDP-glucose, NAD, and bis-p-nitrophenylphosphate were 5% or less as reactive as the nucleoside triphosphates. The pyrophosphohydrolase was inactive toward adenosine 3':5'-monophosphate or various phosphonates. UDP-glucose (1 mM), NAD (1 mM), or RNA (1 mg/ml) failed to inhibit the ATP pyrophosphohydrolase activity. These observations suggest that the ATP pyrophosphohydrolase of the cartilage is probably not a phosphodiesterase I. The matrix vesicle fraction, which probably also included some plasma membrane vesiculated during collagenase digestion, contained the highest specific activity of the enzyme as compared to other subcellular fractions of either epiphyseal or articular cartilage.
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PMID:Purification and partial characterization of ATP pyrophosphohydrolase from fetal bovine epiphyseal cartilage. 621 90

Recent studies in a variety of cell types have revealed several receptor subtypes that bind ATP and trigger increases in intracellular Ca2+ concentration ([Ca2+]i). The present studies were aimed at determining whether similar receptors are present in the rat terminal inner medullary collecting duct (IMCD). [Ca2+]i was measured using fura 2 in tubules dissected from collagenase-treated rat kidneys. ATP (1-100 microM) caused a rapid increase in [Ca2+]i with a prolonged late phase after an initial peak. A similar rise was observed in tubules exposed to UTP or to the poorly hydrolyzable analogue, adenosine 5'-O-(3-thiotriphosphate) (ATP gamma S). In contrast, agonists that bind P2x, P2y, P2z, and P2t purinergic receptors did not affect [Ca2+]i. Removal of extracellular Ca2+ inhibited the response to ATP by approximately 50% with obliteration of the late phase. Furthermore, indomethacin attenuated the rise in [Ca2+]i produced by ATP. Adenosine analogues also increased [Ca2]i apparently by binding to distinct adenosine receptors rather than to the ATP receptor. We conclude that there is a nucleotide receptor in the rat terminal IMCD, which, when occupied, mobilizes intracellular Ca2+.
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PMID:Extracellular ATP increases intracellular calcium in rat terminal collecting duct via a nucleotide receptor. 781 Jul 8

We have prepared purified cytotrophoblasts from human term placentas and examined the sensitivity of fura-2 loaded cells to the nucleotides ATP and UTP and to changes in extracellular Ca2+ concentration ([Ca2+]o). Purified cytotrophoblasts were obtained by collagenase digestion and separation according to density using self-generated Percoll gradients. The cytotrophoblast fraction was free of red cell and largely free of white cell contamination (as assessed by uniformly negative staining for vimentin and the failure of > 90% of fura-2 loaded cells to respond to the chemotactic peptide fMet-Leu-Phe). Purified cells secreted progesterone in a linear fashion over several hours in the presence of 25-hydroxycholesterol. The cells ranged in size from approximately 7.5 to 50 microns in diameter as described previously for purified cytotrophoblasts, and an analysis of cells for sensitivity to [Ca2+]o or nucleotides suggested functional heterogeneity within the cytotrophoblast population. Small cells (7.5-10 microns) were negative for cytokeratin-8 and, after loading with fura-2, were insensitive to extracellular nucleotides but sensitive to elevations in [Ca2+]o. Medium-sized cells (12-20 microns) were largely cytokeratin-positive (70% of cells) and sensitive to both ATP and UTP but largely insensitive to [Ca2+]o. Large cells (25-50 microns) were uniformly cytokeratin-positive (100% of cells) and, after fura-2 loading, sensitive to both [Ca2+]o and extracellular ATP or UTP. We examined the likely origin of small, medium and large cytotrophoblasts using an immunomagnetic cell sorting procedure that separates villous cytotrophoblasts (which do not express major histocompatibility class I antigens) from extravillous cytotrophoblasts. This procedure resulted in the selective sedimentation of almost all medium and large cells, leading to the conclusion that the small cells were villous cytotrophoblasts whereas medium and large cells were predominantly extravillous in origin. The data suggest that small, medium and large cytotrophoblasts have distinct roles in the function of the term placenta.
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PMID:Functional heterogeneity of human term cytotrophoblasts revealed by differential sensitivity to extracellular Ca2+ and nucleotides. 867 46

In the present study we have analyzed the mechanisms of calcium entry and mobilization in smooth muscle cells (SMCs) freshly isolated from the abdominal aorta of rats with bile duct ligation (BDL). The SMCs were obtained in the day of the experiment after collagenase digestion and loaded with fura-2. The intracellular calcium levels ([Ca](i)) were determined in individual cells by fluorescence microscopy. Baseline [Ca](i) was slightly but significantly lower in SMCs from BDL rats (70.14+/-2.02 nM, n=51) than in controls (80.77+/-3.52, n=44). The application of the purinergic agonists ATP and UTP induced a fast calcium peak and a slow return to baseline. But the calcium responses were significantly smaller in the cells from the BDL rats. Also, the area under the curve (AUC) of the calcium responses elicited by the agonists was always lower in the SMCs from BDL rats as compared to the controls. Similar results were obtained with UTP, but the calcium response of the SMCs from the BDL rats was even lower than that observed with ATP. In experiments performed in the absence of extracellular calcium, both agonists also elevated [Ca](i), although the responses were much smaller than those obtained in the presence of calcium. Again, the peak and AUC responses of the SMCs from BDL rats were significantly lower than those of the controls. Incubation with NNA, a non-specific nitric oxide synthase (NOS) inhibitor, or with NIL, an inducible NOS inhibitor (iNOS), potentiated and normalized the calcium responses of the SMCs obtained from BDL rats. These data indicate that, in SMCs from bile duct-ligated rats, both the entry of calcium and the mobilization from internal stores is defective in response to purinergic agonists. NO, of an inducible origin, is involved in this altered calcium regulation.
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PMID:Altered calcium regulation in freshly isolated aortic smooth muscle cells from bile duct-ligated rats: role of nitric oxide. 1253 Nov 89

Tendon cells receive mechanical signals from the load bearing matrices. The response to mechanical stimulation is crucial for tendon function. However, overloading tendon cells may deteriorate extracellular matrix integrity by activating intrinsic factors such as matrix metalloproteinases (MMPs) that trigger matrix destruction. We hypothesized that mechanical loading might induce interleukin-1beta (IL-1beta) in tendon cells, which can induce MMPs, and that extracellular ATP might inhibit the load-inducible gene expression. Human tendon cells isolated from flexor digitorum profundus tendons (FDPs) of four patients were made quiescent and treated with ATP (10 or 100 microM) for 5 min, then stretched equibiaxially (1 Hz, 3.5% elongation) for 2 h followed by an 18-h-rest period. Stretching induced IL-1beta, cyclooxygenase 2 (COX 2), and MMP-3 genes but not MMP-1. ATP reduced the load-inducible gene expression but had no effect alone. A medium change caused tendon cells to secrete ATP into the medium, as did exogenous UTP. The data demonstrate that mechanical loading induces ATP release in tendon cells and stimulates expression of IL-1beta, COX 2, and MMP-3. Load-induced endogenous IL-1beta may trigger matrix remodeling or a more destructive pathway(s) involving IL-1beta, COX 2, and MMP-3. Concomitant autocrine and paracrine release of ATP may serve as a negative feedback mechanism to limit activation of such an injurious pathway. Attenuation or failure of this negative feedback mechanism may result in the progression to tendinosis.
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PMID:ATP modulates load-inducible IL-1beta, COX 2, and MMP-3 gene expression in human tendon cells. 1276 89

Our previous studies document the expression of adrenoceptors and purinoceptors in the rat prostate neuroendocrine cells (RPNECs). However, a direct investigation of the receptors for acetylcholine (ACh) is still lacking in the prostate neuroendocrine cells. RPNECs were freshly isolated from the ventral lobes of rat prostate by using collagenase. Effects of ACh and various muscarinic antagonists on the intracellular Ca(2+) concentration ([Ca(2+)](c)) were investigated by using the fura-2 spectrofluorimetry. Single-cell RT-PCR analysis was applied to identify the transcripts for the muscarinic receptor subtypes. ACh (5 microM) induced a sharp transient increase in the [Ca(2+)](c) of RPNECs, which was independent of the extracellular Ca(2+). In the same RPNECs, high KCl (60 mM), phenylephrine (5 microM), UTP (P2Y(1/2) agonist, 50 microM), and alpha, beta-meATP (P2X(1/3) agonist, 0.5 microM) also increased the [Ca(2+)](c). The ACh-induced [Ca(2+)](c) change (delta [Ca(2+)](c)) was blocked by atropine or by para-fluorohexahydrosiladifenidol (M(3) antagonist, 0.3 microM), but not by telenzepine (M(1) antagonist, 1 microM) and himbacine (M(2) and M(4) antagonist, 1 microM). The single-cell RT-PCR demonstrated the selective expression of mRNAs for M(3) in RPNECs. In summary, RPNECs express M(3) muscarinic receptors that are linked to the release of Ca(2+) from intracellular stores. The Ca(2+) signals of RPNECs might mediate the parasympathetic regulation of prostate gland.
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PMID:M3 subtype of muscarinic receptors mediate Ca2+ release from intracellular stores in rat prostate neuroendocrine cells. 1583 97