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

---

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

1. Angiotensin II increases myocardial contractility in several species, including the rabbit and man. However, it is controversial whether the predominant mechanism is an increase in free cytosolic [Ca2+]i or a change in myofilament Ca2+ sensitivity. To address this question, we infused angiotensin II in isolated perfused rabbit hearts loaded with the Ca2+ indicator indo-1 AM and measured changes in beat-to-beat surface transients of the Ca2+i-sensitive 400:500 nm ratio and left ventricular contractility. The effects of angiotensin II were compared with the response to a Ca(2+)-dependent increase in the inotropic state produced by a change in the perfusate [Ca2+] from 0.9 to 3.6 nM. 2. In the isolated beating heart, an increase in perfusate [Ca2+] caused an increase in left ventricular pressure +dP/dt in association with an increase in peak systolic [Ca2+]i. Angiotensin II perfusion caused a similar increase in left ventricular +dP/dt in the absence of any increase in peak systolic [Ca2+]i. 3. To exclude any contribution of non-myocyte sources of Ca(2+)-sensitive fluorescence which may be present in the intact heart, we also compared the effects of angiotensin II and a change in superfusate [Ca2+] in collagenase-dissociated paced adult rabbit ventricular myocytes loaded with indo-1 AM. In the isolated rabbit myocytes a change in perfusate [Ca2+] from 0.9 to 3.6 mM caused an increase in peak systolic cell shortening coincident with an increase in peak systolic [Ca2+]i. In contrast, angiotensin II caused a similar increase in peak systolic cell shortening whereas there was no increase in peak systolic [Ca2+]i. There was also no change in inward Ca2+ current (ICa) in response to angiotensin II. 4. To investigate further the mechanism of the positive inotropic action of angiotensin II, its effects on intracellular pH were studied in isolated rabbit myocytes loaded with the fluorescent H+ probe SNARF 1. These experiments demonstrated that angiotensin II induced a 0.2 pH unit increase coincident with the development of a positive inotropic effect in isolated rabbit myocytes. 5. In summary, angiotensin II has a direct positive inotropic effect in beating rabbit hearts and in isolated paced rabbit myocytes. These experiments provide support for the hypothesis that the predominant mechanism is not an increase in free cytosolic Ca2+ but is due in part to an increase in myofilament Ca2+ sensitivity due to intracellular alkalosis.
...
PMID:Effects of angiotensin II on intracellular Ca2+ and pH in isolated beating rabbit hearts and myocytes loaded with the indicator indo-1. 786 40

Immortalized rat proximal tubule cell (IRPTC) lines should be useful for investigation of proximal tubule (PT) regulation and function but previously have been unavailable. We now report the establishment and characterization of an immortalized transformed, temperature-sensitive IRPTC cell line containing renin-angiotensin system (RAS) components. Primary PT cells prepared from male Wistar rats (4-5 wk old) after collagenase digestion, sieving, and Percoll gradient were cultured on collagen-coated T-75 flasks in Dulbecco's modified Eagle's medium containing 5% fetal calf serum. Subconfluent PT cells were transfected with the temperature-sensitive SV40 mutant viruses (tsA SV40) by direct exposure. After 7-8 wk, several clones were obtained, from which one has been characterized and designated as line 3-2. This cell line appears stable up to 45 passages. Clonal cells transformed with this virus exhibit a transformed phenotype at a permissive temperature of 34 degrees C and grow in multiple layers. When the cells are subsequently placed at a nonpermissive temperature of 41 degrees C, they return to morphology similar to that of untransformed cells of the same lineage. At either 34 degrees C or 41 degrees C, this cell line expresses a variety of PT markers including alkaline phosphatase, cytokeratin, carbonic anhydrase, and glucose transporter isoform 2 (GLUT2), while not expressing factor VIII. Uniquely, these cells also appear to express PT proteins gp330 and CHIP28, markers which are usually lost in cultured cells. Furthermore, the cell line expresses protein and mRNA components of RAS, including angiotensinogen, angiotensin converting enzyme, and renin. The IRPTC cell line expresses few angiotensin II (ANG II) receptors at 34 degrees C, the permissive temperature. However, at the nonpermissive temperature, 41 degrees C, IRPTC expresses ANG II receptor (dissociation constant of 0.7 nM; maximum binding capacity of 265 fmol/mg protein). ANG II (10(-8) M) induced a transient rise in cytoplasmic Ca2+ concentration, which was nearly abolished with losartan but not PD-123319, suggesting this finding is AT1 receptor mediated. This cell line should provide an excellent model of PT and should make it possible to study the cell and molecular biology of the RAS, as well as other regulatory systems of the PT.
...
PMID:Temperature-sensitive SV40 immortalized rat proximal tubule cell line has functional renin-angiotensin system. 790 Aug 43

Myocardial fibrosis is associated with an activated renin-angiotensin-aldosterone system (RAAS). In renovascular hypertension, this presents as a reactive perivascular and interstitial fibrosis in not only the pressure overloaded, hypertrophied left ventricle but also the normotensive, nonhypertrophied right ventricle. It therefore would appear that circulating hormonal and not hemodynamic factors are responsible for this adverse fibrous tissue response. To ascertain whether the RAAS effector hormones angiotensin II (AII) or aldosterone (ALDO) directly stimulate collagen synthesis or inhibit collagenase production we used cell culture. Adult rat cardiac fibroblasts (Fb) were cultured since these cells express mRNA for types I and III collagens, the major fibrillar collagens in the heart, and collagenase or matrix metalloproteinase 1 (MMP 1), the key enzyme for interstitial collagen degradation. Collagen synthesis, determined by 3H-proline incorporation, and collagenase activity were measured in confluent, quiescent Fb after 24 h incubation with various concentrations of AII or ALDO (10(-11)-10(-6)M) in the presence or absence of either 10(-5)M type 1 (DuP 753) and type 2 (PD 123177) AII or 10(-9)-3 x 10(-6)M ALDO (spironolactone) receptor antagonists, respectively. Collagen synthesis, normalized per total protein synthesis, increased significantly (P < 0.005) after incubation with either 10(-9)M ALDO (5.9 +/- 1.0%) or 10(-7)M AII (5.3 +/- 1.2%) compared with untreated control cells (2.9 +/- 0.5%) of the same passage (p6-p10). This increase in collagen synthesis could be completely abolished by either types 1 or 2 AII receptor antagonists in AII stimulated Fb or the competitive ALDO receptor antagonist, spironolactone, at equimolar concentration in ALDO stimulated Fb. AII significantly decreased collagenase activity which could be completely abolished by PD 123177, but not DuP 753, while ALDO had no effect on collagenase activity. The mineralocorticoid, ALDO, stimulates collagen synthesis in cultured adult rat cardiac Fb in concentrations similar to those found in plasma in renovascular hypertension and this response appears to occur via type I corticoid receptors. AII appears to stimulate collagen synthesis by both type 1 and 2 AII receptors, but only in high concentrations that could be generated locally within the myocardium. In addition, AII unlike ALDO inhibits collagenase activity that could be attenuated only by type 2 receptor blockade. These findings suggest a direct interaction between ALDO, AII and cardiac Fb in mediating myocardial fibrosis in hypertensive heart disease.
...
PMID:Collagen metabolism in cultured adult rat cardiac fibroblasts: response to angiotensin II and aldosterone. 796 49

A collagen network, composed largely of type I and III fibrillar collagens, is found in the extracellular space of the myocardium. This network has multiple functions which includes a preservation of tissue architecture and chamber geometry. Given its tensile strength, collagen is a major determinant of tissue stiffness. Its disproportionate accumulation, in the form of either a reactive or a reparative fibrosis, further increases stiffness. A degradation of collagen tethers, on the other hand, is an anatomic requisite for a distortion in tissue architecture and a reduction in stiffness that can lead to chamber dilatation, wall thinning, and even rupture of the myocardium. Collagen turnover in the myocardium is dynamic. When synthesis exceeds degradation, an adverse accumulation of collagen appears to distort tissue structure. This is true for either the hypertrophied and/or nonhypertrophied ventricle. Factors that contribute to the appearance of myocardial fibrosis are largely different from those that promote cardiac myocyte growth. Included amongst these fibrogenic factors are effector hormones of the reinin-angiotensin-aldosterone system (RAAS). Studies conducted both in intact animals (relative to dietary sodium intake) and in cultured adult cardiac fibroblasts have pointed toward the association between collagen accumulation and chronic elevations in circulating angiotensin II and aldosterone. A tissue hormonal system involving angiotensin II, endothelins and bradykinin, may likewise regulate fibrogenesis. In this regard, angiotensin converting enzyme is found in connective tissue of the normal heart, including the matrix of heart valves and the adventitia of the intramural coronary arteries, and fibrous tissue that forms following infarction or with chronic RAAS activation. The importance of ACE in the regulation of local angiotensin II and bradykinin levels and their contribution to collagen turnover is a fruitful area of research with important clinical implications. The myocardium also contains a proteolytic system, including collagenase. The characteristics and regulation of matrix metalloproteinases and their tissue inhibitors in various cardiovascular disease states requires further investigation.
...
PMID:Collagen network of the myocardium: function, structural remodeling and regulatory mechanisms. 802 11

We cultured smooth muscle cells as explants from rat mesenteric arterioles (40-200 microns in diameter) obtained by injecting a suspension of iron oxide intraarterially and magnetically separating the arterioles after collagenase digestion of adventitial tissue. In third-passaged cells we ascertained smooth muscle purity of > 98% by characteristic morphology, contraction responses, and specific immunofluorescence staining. Treatment of growth-arrested (in 0.4% fetal calf serum) cells with platelet-derived growth factor (0.3-7.5 nM) or angiotensin II (0.001-1000 nM) induced 3H-thymidine incorporation and cell proliferation in a dose-dependent manner (P < 0.01). S-nitroso-N acetylpenicillamine (0.05-0.5 mM), a nitric oxide-generating compound, inhibited 10% fetal calf serum-induced 3H-thymidine incorporation (P < 0.05) and cell proliferation (P < 0.01). The antimitogenic effect of S-nitroso-N-acetylpenicillamine was significantly reduced by hemoglobin and potentiated by superoxide dismutase (P < 0.01). In addition to a new technique for culturing mesenteric arteriolar smooth muscle cells, these findings provide evidence that platelet-derived growth factor, angiotensin II, and nitric oxide may be involved in their growth control.
...
PMID:Culture of rat mesenteric arteriolar smooth muscle cells: effects of platelet-derived growth factor, angiotensin, and nitric oxide on growth. 811 39

Contractions of the rat uterus in response to trypsin, kallikrein, bradykinin, angiotensin II, oxytocin and acetylcholine, were abolished when an inside-out preparation was used. Sensitivity to Ba++, however, was preserved. In preparations in which the endometrium was mechanically removed, all above cited agonists elicited contractions. By treating the uterus with both collagenase and hyaluronidase, acetylcholine was able to induce a contraction when applied to the endometrium side of the uterus. The results show that a barrier for protease, peptides and acetylcholine is present in the mucosa of the rat uterus.
...
PMID:Pharmacological demonstration of a barrier for protease, peptides and acetylcholine in the endometrium of the rat. 818 17

The cardiac interstitium is composed of non-myocyte cells embedded in a highly organized extracellular matrix containing a three-dimensional collagen network which serves to maintain the architecture of the myocardium and determines myocardial stiffness. In hypertensive heart disease, a heterogeneity in myocardial structure, created by the altered behaviour of cardiac fibroblasts responsible for collagen synthesis and degradation, can explain the appearance of diastolic and ultimately systolic dysfunction of the left ventricle. In vivo, circulating and myocardial renin-angiotensin systems (RAS) were found to be involved in the regulation of the structural remodelling of the cardiac interstitium. In vitro, in cultured adult rat cardiac fibroblasts, angiotensin II was shown to stimulate collagen synthesis and to inhibit collagenase activity, which is the key enzyme for collagen degradation. In the SHR-model of primary hypertension, left ventricular hypertrophy could be regressed and abnormal myocardial diastolic stiffness, due to interstitial fibrosis, could be restored to normal by inhibition of the myocardial RAS. These antifibrotic or cardioreparative effects of ACE inhibition that occurred irrespective of blood pressure normalization may be valuable in reversing left ventricular diastolic dysfunction in hypertensive heart disease.
...
PMID:Renin-angiotensin system and myocardial fibrosis in hypertension: regulation of the myocardial collagen matrix. 828 64

The effects of endothelin-1 (ET-1) on protein synthesis and phosphoinositide (PI) hydrolysis were investigated in ventricular myocytes isolated by collagenase digestion of adult rat hearts. The maximum stimulation of protein synthesis by ET-1 was about 35% and the EC50 value was about 0.3 nM. The stimulation was exerted at the translational stage since it was insensitive to inhibition by actinomycin D. The maximum stimulation of PI hydrolysis by ET-1 as measured by the formation of [3H]inositol phosphates was about 11-fold and the EC50 value was about 0.7 nM. The ET-1 analogue sarafotoxin-6b stimulated protein synthesis by a maximum of 27% and stimulated PI hydrolysis about 8- to 9-fold. The EC50 values were 1.6 nM and 0.6 nM, respectively. Other endothelins stimulated protein synthesis and PI hydrolysis in the following order of potency: ET-1 approximately ET-2 > ET-3. This order of potency suggests that the stimulation of both protein synthesis and PI hydrolysis is mediated through the ETA receptor. Although both angiotensin II and [Arg]vasopressin stimulated PI hydrolysis significantly, the stimulation was less than 60%, i.e., much less than the stimulation by ET-1 and its analogues. Neither insulin nor substance P stimulated PI hydrolysis. Stimulation of protein synthesis by ET-1 and its analogues correlated strongly with the stimulation of PI hydrolysis and we suggest that the stimulation of protein synthesis may be dependent on the stimulation of PI hydrolysis. We hypothesize that the mechanism may involve a protein kinase C-mediated increase in intracellular pH.
...
PMID:Stimulation of adult rat ventricular myocyte protein synthesis and phosphoinositide hydrolysis by the endothelins. 838 85

The interstitial space of the myocardium is composed of nonmyocyte cells and a highly organized collagen network which serves to maintain the architecture and mechanical behavior of the myocardial walls. It is the myocardial collagen matrix that determines myocardial stiffness in the normal and structurally remodeled myocardium. In hypertensive heart disease, the heterogeneity in myocardial structure, created by the altered behavior of nonmyocyte cells, particularly cardiac fibroblasts which are responsible for collagen synthesis and degradation, explains the appearance of diastolic and/or systolic dysfunction of the left ventricle that leads to symptomatic heart failure. Several lines of evidence suggest that circulating and myocardial renin-angiotensin systems (RAS) are involved in the regulation of the structural remodeling of the nonmyocyte compartment, including the cardioprotective effects of angiotensin converting enzyme (ACE) inhibition that was found to prevent myocardial fibrosis in the rat with renovascular hypertension. In cultured adult rat cardiac fibroblasts angiotensin II was shown to directly stimulate collagen synthesis and to inhibit collagenase activity, which is the key enzyme for collagen degradation, that would lead to collagen accumulation. In the spontaneously hypertensive rat, an appropriate experimental model for primary hypertension in man, left ventricular hypertrophy could be regressed and abnormal myocardial diastolic stiffness due to interstitial fibrosis could be restored to normal by inhibition of the myocardial RAS. These antifibrotic or cardioreparative effects of ACE inhibition that occurred irrespective of blood pressure normalization may be valuable in reversing left ventricular diastolic dysfunction in hypertensive heart disease.
...
PMID:Renin-angiotensin system and myocardial collagen matrix remodeling in hypertensive heart disease: in vivo and in vitro studies on collagen matrix regulation. 851 39

The purpose of this study was to compare coronary and interstitial endothelin-1 (ET-1) levels in perfused rat hearts under several experimental conditions, because the cardiac tissue concentration of ET-1 is not clear. Hearts were perfused in an upside-down position with a colloid-free buffer at a constant flow rate of 9 ml/min/g heart wet weight, and immunoreactive ET-1 was determined in timed collections of coronary effluent and interstitial transudate produced by the ventricles and appearing on their surface. Basal ET-1 release into effluent was 0.26 +/- 0.007 pg/min/g, and 0.005 +/- 0.0012 pg/min/g in transudate. Basal ET-1 concentration was 0.11 +/- 0.005 pg/ml (transudate) and 0.03 +/- 0.002 pg/ml (effluent), indicating four-fold higher transudate than effluent levels (P < 0.05). Following perfusion of hearts with collagenase to remove endothelial cells, ET-1 release into effluent was reduced to one-third and completely abolished in transudate, indicating that the peptide originated from the vascular endothelium. Perfusion of hearts with angiotensin II (0.1 mumol/l) or thrombin (5 U/ml) increased coronary perfusion pressure and ET-1 secretion, but little affected the transudate/effluent ET-1 concentration ratio (5.5 and 3.2, respectively). When coronary flow was reduced to ischaemic level (1 ml/min/g over several hours), ET-1 secretion rates into effluent were decreased by 55-65%, but increased three- to four-fold on reperfusion at normal flow (P < 0.05). The ET-1 concentrations in both fluids were still always below 1 pg/ml. No change in coronary perfusion pressure compared to time-matched normoxic controls was observed. In the presence of the ET-1 converting enzyme inhibitor, phosphoramidon (1.7 mumol/l), ischaemia-induced increases of ET-1 secretion were attenuated, and this was accompanied by a time-dependent rise in coronary perfusion pressure up to 60% (P < 0.05). These are the first measurements of endogenous cardiac tissue ET-1 levels; they do not support a vasoconstrictor (pro-ischaemic) action of endogenous ET-1 in rat hearts following ischaemia/reperfusion, but rather point to a possible vasodilator role of the peptide under these conditions.
...
PMID:Tissue endothelin-1 levels in perfused rat heart following stimulation with agonists and in ischaemia and reperfusion. 852 55


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---