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)

Using isolated glomeruli and nephron segments obtained from collagenase treated rabbit kidneys, we examined the in vitro degradation of alpha-human atrial natriuretic polypeptide (alpha-hANP). The ANP-degrading activity was measured by the amount of immunoreactive ANP remaining after incubation of about 50 fmoles alpha-hANP with each tissue preparation for 7.5 min. The sequence of degrading activity among isolated nephron segments was as follows: proximal straight tubule greater than proximal convoluted tubule greater than cortical collecting tubule greater than distal convoluted tubule greater than cortical thick ascending limb. A single glomerulus exhibited the degrading activity which was comparable to approximately 50% of the activity of 1 mm proximal convoluted tubule. Phosphoramidon, an inhibitor of endopeptidase, prevented the degradation of ANP in proximal convoluted tubule and glomerulus by 68% and 89%, respectively, but not in cortical thick ascending limb and cortical collecting tubule. From these results, we conclude that the degradation of ANP by endopeptidase occurs mainly in the proximal tubule and glomerulus.
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PMID:Intrarenal localization of degradation of atrial natriuretic peptide in isolated glomeruli and cortical nephron segments. 296 44

The distribution of kininases along microdissected nephron segments was studied. Single nephrons from collagenase treated rabbit kidney were microdissected and divided into following 9 segments: glomerulus; early proximal tubule; middle proximal tubule; late proximal tubule; cortical thick ascending limb; distal convoluted tubule; connecting tubule; cortical collecting tubule; medullary collecting tubule. Kininase activities in these nephron segments were measured with or without kininase II inhibitor. Kininase II and other peptidases were mainly localized in glomeruli and whole part of the proximal tubules.
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PMID:Distribution of kininase activity along the rabbit nephron. 303 11

Prostaglandin E2 (PGE2) content and synthesis have been measured in microdissected segments from the entire nephron of rabbit kidney. PGE2 was determined by an enzyme immunoassay on glomeruli or tubular segments (0.5-5 mm) either immediately after microdissection (PGE2 content) or after incubation for 15 min at 37 degrees C in the presence of arachidonic acid (PGE2 synthesis). We confirmed that collagenase used for microdissection did not modify PGE2 synthesis. A linear correlation was found between the length of tubule used in the assay and PGE2 synthesis, as well as between incubation time with arachidonic acid and PGE2 synthesis. PGE2 synthesis, expressed in picograms per millimeter tubular length per 15 min, was maximum in medullary collecting duct (517 +/- 73). High values were also found in the granular portion of distal tubule (134 +/- 22) and granular or light portion of cortical collecting tubule (199 +/- 24 and 146 +/- 10, respectively). Synthesis was lower in all other segments: 17 +/- 6 and 24 +/- 12, respectively, in convoluted and straight proximal tubule, 67 +/- 12 and 71 +/- 5, respectively, in thin descending and ascending limb, 51 +/- 9 and 23 +/- 4, respectively, in medullary and cortical thick ascending limb of Henle's loop, and 25 +/- 7 in initial distal tubule. Synthesis per glomerulus was 24 +/- 3. When the protein content of each nephron segment is taken into account, this profile was not modified, except for the thin limbs of the loop, which reached values per nanogram protein slightly higher than those of the cortical collecting tubule.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Determination of prostaglandin E2 synthesis along rabbit nephron by enzyme immunoassay. 309 Aug 97

The effect of vasoactive intestinal peptide (VIP) upon adenylate cyclase (AC) activity has been determined in defined microdissected renal tubules isolated from collagenase-treated rabbit kidneys. In the presence of 10 microM GTP, 1 microM VIP gave marked stimulations of AC over basal values in the bright portion of the distal convoluted tubule (DCTb) (10.1-fold), and in the collecting tubule isolated from the inner stripe of the outer medulla (OMCTi, 7.8-fold). Less pronounced effects of VIP were found in the medullary collecting tubule isolated from the outer stripe (2.5-fold) and in the granular portion of the distal convoluted tubule (2.0-fold). VIP stimulation of AC activity in these segments amounted to 25 to 40% of the effect elicited by other agonists (arginine vasopressin, calcitonin or parathyroid hormone) in their respective target segments. A low response to VIP was observed in the cortical thick ascending limb (1.8-fold) which represented less than 5% of the calcitonin-stimulated AC activity. In the thin descending limb VIP produced a slight and variable stimulation of AC. VIP was without effect upon AC in the convoluted and straight portions of the proximal tubule, the medullary thick ascending limb and the cortical collecting tubule. Half-maximal stimulation of AC by VIP was observed at 26 +/- 10 nM (n = 3) in OMCTi and at 19 nM (n = 2) in DCTb. Related peptides glucagon, secretin and PHI gave lower stimulations of AC compared to VIP in OMCTi. Conversely for rat OMCTi, under identical conditions, glucagon was much more effective than VIP.
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PMID:Distribution of vasoactive intestinal peptide-sensitive adenylate cyclase activity along the rabbit nephron. 317 93

The activities of DNA polymerase alpha and key enzymes of gluconeogenesis and glycolysis were measured in different segments of the rat nephron at various times (up to 96 hrs) following a unilateral nephrectomy (UNx). Tubule fragments were obtained after collagenase treatment followed by centrifugation on a Percoll gradient. The DNA polymerase alpha activity in control rats showed moderate and similar values in different segmental extracts as well as in the whole kidney extract (1700-1800 mumumole [3H] dAMP/mg DNA). In UNx rats, activity in proximal tubules (PT) measured at 24, 48, 72 and 96 hrs after nephrectomy represented an increase of 60%, 200%, 420% and 370% respectively over control values. Distal tubule fragments (DT) showed only minor increases. The results demonstrate that the proximal tubule accounts for most of the compensatory renal growth (CRG) in the remaining kidney. The gluconeogenic and glycolytic enzymes were confined to the PT and those of glycolysis to the DT fragments. Following UNx, the specific activities of these enzymes were not modified in the remaining kidney; however, the overall activity of gluconeogenesis was increased as a result of the cell hyperplasia occurring in the PT. Our work also illustrates that biochemical studies of CRG on the whole organ may provide misleading information due to the presence of heterogenous cell populations in the mammalian kidney and to their uneven response in CRG.
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PMID:Segmental heterogeneity of enzymatic response during compensatory renal growth. 383 6

To locate the sites of dopamine (D) production in rat renal cortex, we separated glomeruli and proximal tubules by sieving or centrifugation in Percoll after collagenase digestion. After centrifugation layer I contained 60-80% glomeruli and 20-40% tubule fragments, half of which did not stain with alkaline phosphatase, layer II contained 0-5% glomeruli, 10-25% tubule fragments other than proximal tubules, and 70-85% proximal tubule fragments. Layer IV contained 85-95% proximal tubules. Gluconeogenic rates were (micromoles per hour per gram wet weight) as follows: I, 4 +/- 1; II, 7 +/- 2; and IV, 16 +/- 1. Norepinephrine (NE) content was (picomoles per gram wet weight) I, 310 +/- 30; II, 540 +/- 40; IV, 195 +/- 60. D content was (picomoles per gram wet weight) I, 26 +/- 6; II, 46 +/- 13; IV, 33 +/- 7. Surgical denervation 4-6 days previously reduced the norepinephrine content of layers I and II to 35 +/- 10 (p less than 0.001) and of IV to 60 +/- 20 (p less than 0.05) and the D content of layers I and II to 13 +/- 6 and 6 +/- 6 pmol/g, respectively (p less than 0.01); D content of layer IV was unchanged. D production from 10(-7) M 3,4-dihydroxyphenylalanine (DOPA) was (nanomoles per gram per minute) I, 0.2 +/- 0.03; II, 0.7 +/- 0.1; IV, 1.0 +/- 0.04. DOPA consumption was (nanomoles per gram per minute) I, 0.6 +/- 0.1; II, 1.4 +/- 0.3; and IV, 1.8 +/- 0.2. Denervation did not change D production or DOPA consumption.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Dopamine production by isolated glomeruli and tubules from rat kidneys. 398 98

A method is described for the preparation of an enriched population of proximal tubules from the cortices of neonate (21-28 d old) rabbits. The method uses collagenase-hyaluronidase digestion, followed by gentle shear to yield a suspension of tubules and glomeruli. Tubular enrichment is achieved by discontinuous density gradient centrifugation in a Percoll gradient. Two fractions were obtained by this method. The denser fraction contained predominantly proximal tubules, was depleted of glomeruli and was enriched in the proximal tubule marker enzyme alkaline phosphatase. Qualitatively similar results to those obtained with neonate animals were obtained with adult tissue. Neonate tubules from the denser gradient fraction grew readily in tissue culture. When examined by electron microscopy the cells exhibited a marked polarity of ultrastructural organization and retained apical tight junctions. Despite this, there was an obvious loss of structure in comparison with in vivo proximal tubule cells. The use of primary culture techniques to study in vitro renal epithelial function is discussed.
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PMID:Isolation and culture of renal cortical tubules from neonate rabbit kidneys. 612 33

A homogeneous population of single cells from the thick ascending limb of Henle's loop (TALH) has been isolated from the rabbit kidney medulla. A total medullary cell suspension was prepared by a series of collagenase, hyaluronidase, and trypsin digestions and separated on a Ficoll gradient (2.6-30.7% wt/wt). Morphologically, the cells isolated from the TALH were homogeneous and showed polarity within their plasma membrane structure, with a few blunt microvilli on their apical surface and deep infoldings of the basal-lateral membrane. Biochemically, the TALH cells were highly enriched in calcitonin-sensitive adenylate cyclase and Na, K-ATPase. Alkaline phosphatase and arginine vasopressin-sensitive adenylate cyclase, highly concentrated in proximal tubule and collecting duct, were present only in low concentrations in the TALH cells. Additionally, furosemide, a diuretic inhibiting sodium chloride transport in the TALH in vivo, inhibited oxygen consumption of the TALH cells in a dose-dependent manner. The TALH cells were viable, as judged by morphological appearance, trypan blue exclusion, the response of oxygen consumption to 2,4-dinitrophenol, succinate and ouabain, and the cellular Na, K and ATP levels.
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PMID:Separation of renal medullary cells: isolation of cells from the thick ascending limb of Henle's loop. 625 27

The sites of action of aldosterone (A) along the tubule of rabbit kidney were studied by autoradiographic localization of mineralocorticoid-binding sites on microdissected tubular segments. Kidney pyramids were incubated at 30 degrees C for 1 h in a collagenase solution with [3H]aldosterone at a concentration of 1.5 X 10(-9) M with and without an excess unlabeled A. Tubular segments were then microdissected and transferred onto dry film; fixation and staining were done only after exposure of the film 4 mo later in order to avoid diffusion. Specific nuclear labeling was 19.0 +/- 1.3 silver grains/100 micrometers2 in distal convoluted tubules (n = 28) and 21.0 +/- 1.8 in cortical collecting ducts (n = 18). No difference between these two structures was observed (P greater than 0.1, paired t test, n = 15). No specific binding was found in the proximal tubule (0.5 +/- 0.4, n = 17). In the thick ascending limb of Henle's loop, the labeling was low (3.9 +/- 0.9, n = 16). We conclude that, in the rabbit kidney, nuclear mineralocorticoid-binding sites, presumably receptors, are present in the distal and cortical collecting tubule.
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PMID:Aldosterone binding along the rabbit nephron: an autoradiographic study on isolated tubules. 625 52

Gentamicin is a nephrotoxic antibiotic of the aminoglycoside group, which accumulates within the renal cortex. The present study is an attempt to localize precisely the sites of gentamicin accumulation along isolated tubular segments. We performed autoradiography of 3 H-gentamicin (3H-G) uptake on isolated tubules from kidneys of 6 rabbits previously treated by a single dose of this drug (125 muCi/kg of body wt; 140 microgram/kg of body wt). Isolated tubules were obtained by microdissection following collagenase incubation, 4 hours after 3H-G administration. Autoradiography of single isolated tubular segments was performed according to a dry-film technique. Results were as follows. Almost no gentamicin incorporation (less than 2 silver grains per 150 micrometer2) takes place along the distal parts of the nephron, from the beginning of the loop of Henle to the end of the medullary collecting duct. No differences were visible along these parts of the nephron, whatever their localization, cortical or medullary, In the proximal tubule (PT), we observed a gradual regular increase in 3H-G accumulation, from the glomerulus to the end of the pars recta. The silver grain density progressively increased along this structure from the very early PT (5 per 150 micrometer2) to the last millimeter of the pars recta (40 per 150 micrometers). No clear difference between superficial and juxtamedullary nephrons was detected. The possible mechanisms that could account for this observed variation in 3H-G cellular uptake along the PT are discussed.
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PMID:Gentamicin incorporation along the nephron: autoradiographic study on isolated tubules. 724 87


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