Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.24.3 (collagenase)
 18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The epithelium of the urinary bladder of Bufo marinus is composed of 5 cell types, i.e., granular (Gr), mitochondria-rich (MR) and goblet (G) cells which face the urinary lumen, microfilament-rich (MFR) and undifferentiated cells (Un) located basally. The epithelium was dissociated by collagenase and EGTA treatment. Fractionation of dispersed cells by isopycnic centrifugation on dense serum albumin solutions yielded 4 fractions: (i) a very light fraction (p approximately equal to 1.025) enriched in MR and MFR cells; (ii) a light fraction (p approximately equal to 1.045) enriched in vacuolated Gr cells; (iii) a heavy fraction (p approximately equal to 1.065) composed essentially of aggregated Gr cells, and (iv) a pellet (p approximately equal to 1.085) enriched in G and undifferentiated cells. Recoveries were based on cell counts and DNA measurements. DNA content per cell was 13.2 pg +/- 0.9 (n = 37). From 1 g fresh tissue, 62 +/- 5 x 10(6) (n = 10) cells were recovered before isopycnic centrifugation of which about 70% excluded Trypan blue. After centrifugation, 90 to 95% of the cells excluded the vital dye and approximately 3(9) x 10(6) cells were recovered from the gradient. Cell metabolism in each fraction was estimated by oxygen consumption measurements in absence or presence of ouabain, acetazolamide, and dinitrophenol. The consumption measurements in absence or presence of ouabain, acetazolamide, and dinitrophenol. The consumption was threefold higher in the very light and light fractions when compared to the heavy and pellet fractions. Ouabain sensitive oxygen consumption (QO2) represented 12 to 35% of the total O2 consumption depending on the cell fraction, and acetazolamide sensitive QO2 varied from -0.8% in the heavy fractions to 20% in the lighter fractions. DNP increased QO2 in all fractions by 20 to 50%. Finally, the cells were able to reaggregate and form junctional complexes upon addition of calcium to the medium.
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PMID:Isolation and separation of toad bladder epithelial cells. 11 48

Radioactive tracer (42K) flux techniques were used to determine transmembrane K+ influx and efflux in isolated cardiac myocytes. Ca2+-tolerant adult feline ventricular myocytes were isolated by retrograde perfusion of the coronary arteries with a collagenase-containing solution. The isolated cells had intracellular Na+ (17.2 +/- 0.2 mM) and K+ (135.0 +/- 3.9 mM) concentrations that were stable over time. 42K influx and efflux were both described by a single exponential function. The rate constant describing 42K influx was 5.86 +/- 0.40 X 10(-2) min-1, and the calculated total K+ influx was 18.4 +/- 1.6 pmol X cm-2 X s-1. Ouabain produced a dose-dependent decrease in K+ influx with maximal inhibition at 10(-4) M. In the presence of 10(-4) M ouabain, total K+ influx was resolved into both active (ouabain-sensitive 12.2 pmol X cm-2 X s-1) and passive (ouabain-insensitive 6.2) components. The rate constant describing 42K efflux was 6.46 +/- 0.50 X 10(-2) min-1, and the calculated total K+ efflux was 22.0 +/- 1.5 pmol X cm-2 X s-1. K+ efflux was not significantly altered (P greater than 0.5) in the presence of 10(-4) M ouabain. The absolute magnitudes of total K+ influx and efflux were not significantly different (P greater than 0.1), thus suggesting that the cells were in a steady state with respect to K+. These studies demonstrate that transmembrane tracer kinetics and K+ fluxes were readily described using isolated adult cardiac myocytes and that both the active and passive components of these unidirectional fluxes were identified in the presence of ouabain.
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PMID:Transmembrane potassium fluxes in isolated feline ventricular myocytes. 399 1

1. A method was devised for the isolation of islets of Langerhans from rabbit pancreas by collagenase digestion in order to study the influx and efflux of K(+) in islets during insulin secretion. 2. Glucose-induced insulin release was accompanied by an increased rate of uptake of (42)K(+) by the islets of Langerhans, though this was not the case for secretion in response to tolbutamide. Ouabain significantly inhibited the uptake of (42)K(+) by islet tissue. 3. No significant increase in the rate of efflux of (42)K(+) was demonstrated during active insulin secretion. 4. Slices of rabbit pancreas were incubated in media of different K(+) content, and rates of insulin release were determined. Alteration of the K(+) concentration of the medium between 3 and 8mm had no effect on the rate of insulin release by pancreas slices. However, decrease of the K(+) concentration to 1mm resulted in inhibition of secretion in response to both glucose and to tolbutamide. Conversely, an increase in K(+) concentration increased rates of insulin release in response to both these stimuli. 5. It is concluded that, though unphysiological concentrations of K(+) may influence the secretion of insulin, fluxes of K(+) in the islets do not appear to be important in the initiation of insulin secretion.
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PMID:Potassium ions and the secretion of insulin by islets of Langerhans incubated in vitro. 429 39

1. A method to separate the epithelium from the underlying layers of the frog skin is described. The method is based on the combined use of collagenase and hydrostatic pressures.2. The potential difference and the short-circuit current values of isolated epithelia and whole skins are similar. Na net flux and short-circuit current are equivalent.3. The time course of changes in potential following rapid changes in composition of the bathing solutions shows that the barrier to K diffusion at the internal surface of the isolated epithelium is larger than the barrier to Na diffusion at the external surface.4. In the isolated epithelium there are 133 m-mole K(+) and 24.7 m-mole Na/l. cellular water. The amount of extracellular water was considered to be equal to the inulin space.5. Arginine vasopressin (0.1 u./ml.) markedly increased short-circuit current and potential difference in isolated epithelia. The amount of Na in the epithelium that equilibrated with Na in the external solution was not increased by the hormone.6. Ouabain (10(-4)M) reduced short circuit current and potential difference to values close to zero. The ouabain treated epithelia contained an increased amount of Na originating in the internal solution. On the other hand the amount of Na that originated from the external solution was not increased.7. The amount of epithelial Na that equilibrated with Na in the external solution was 0.009 mu-equiv/cm(2). This figure is about ten times smaller than the values found in whole skins.
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PMID:Sodium transport across the isolated epithelium of the frog skin. 432 24

The effects of ouabain, atrial natriuretic peptide, angiotensin-II and potassium on aldosterone production by collagenase dispersed rat zona glomerulosa cells were studied. A-II and 10(-4) M ouabain-induced increases in aldosterone production was inhibited by 10(-9) M ANP at all potassium concentrations examined. 10(-4) M ouabain inhibited the A-II induced increase in aldosterone production at all potassium concentrations. The degree of this inhibition was smaller at higher potassium levels. Ouabain enhanced the inhibitory effect of ANP on A-II-induced aldosterone synthesis at all potassium concentrations. Interactions between A-II, ANP, ouabain and potassium may be of physiological significance in the regulation of aldosterone secretion.
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PMID:Interactions between ouabain, atrial natriuretic peptide, angiotensin-II and potassium: effects on rat zona glomerulosa aldosterone production. 960 Mar 26