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)

Oocytes of 40% of Xenopus laevis frogs respond to acetylcholine (ACh). Oocytes of the majority of responders exhibit the common two-component depolarizing muscarinic response (mean amplitude of the rapid component, 54 nA). Oocytes of approximately 10% of the responders ("variant" donors) exhibit a muscarinic response characterized by a very large transient, rapid current (mean amplitude 1242 nA, reversal potential -33 mV). Responses in oocytes of variant donors exhibit further qualitative differences: pronounced desensitization (absent in oocytes of common donors), characteristic prolonged latency (5.4 vs 0.9 s in oocytes of common donors) and marked inhibition of the response by activators of protein kinase C. Rapid responses in oocytes of variant donors are usually increased by treatment with collagenase, which, in common oocytes, often results in a complete loss of the response that correlates with the loss of muscarinic ligand binding. The number of muscarinic receptors was similar in oocytes of both types of donors (2.2 vs 3.0 fmol/oocyte). Also, the responses of oocytes of variant donors to microinjections of CaCl2 or inositol 1,4,5-trisphosphate were similar to those found in cells of common donors. These findings imply that altered receptor number, calcium stores and/or chloride channel density are not responsible for the variant responses. However, ACh caused an sixteen-fold greater efflux of 45Ca in oocytes of variant donors (35 vs 2.2% of total label in oocytes of common donors). Hence, the characteristics of the variant response may be related to a more efficient coupling between receptor stimulation and the mobilization of cellular calcium.
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PMID:Two types of intrinsic muscarinic responses in Xenopus oocytes. I. Differences in latencies and 45Ca efflux kinetics. 196 11

Segments of mammalian, including human, skeletal muscle 1-2 cm long can be induced to shed vesicles by treatment with collagenase in a high-KCl solution containing no added calcium. The vesicles are encompassed by clean sarcolemma so that the gigaseal necessary for patch-clamping is readily formed. The properties of inwardly rectifying potassium channels and of calcium-activated potassium channels in patches detached from such vesicles are shown to be consistent with expectations based on earlier studies on intact muscle fibers and with patch clamp results on the same type of channels in other tissues. A chloride channel which rectifies outwardly with a conductance ranging from 15 to 50 pS is also described. The utility of sarcolemmal vesicles for the study of ion channels in human biopsy material is discussed.
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PMID:Single-channel activity in sarcolemmal vesicles from human and other mammalian muscles. 246 Jul 68

1. Adenosine triphosphate (ATP), applied in the bathing solution or ionophoretically, depolarized freshly dispersed single arterial smooth muscle cells obtained by collagenase and elastase treatment of the rabbit ear artery. 2. Ionophoretic application of ATP evoked an inward current with a latency of about 70 ms and a time to peak of about 230 ms in cells held under voltage clamp using whole-cell patch-pipette techniques. 3. Bath application of 10 microM-ATP evoked a transient inward current at negative holding potentials. The amplitude of the ATP-induced current was linearly related to the clamp potential with a reversal potential near 0 mV. Removal of extracellular calcium, buffering intracellular calcium with high EGTA concentration, or depleting calcium stores with caffeine or noradrenaline treatment did not affect the ATP-evoked current. 4. Changing the chloride concentration gradient by decreasing extracellular or intracellular chloride concentration, or using the chloride channel blocker, frusemide, had no effect on the currents. 5. Replacing sodium with Tris shifted the reversal potential to more negative potentials. The reversal potential was not affected by exchanging intracellular potassium for caesium or sodium. Replacing extracellular sodium with 89 mM-barium also had little effect on the reversal potential. 6. These results are consistent with ATP activating a conductance that is cation selective but allows both monovalent and divalent cations to pass across the membrane.
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PMID:Action of externally applied adenosine triphosphate on single smooth muscle cells dispersed from rabbit ear artery. 311 14

1. Phenotypical similarities between ICl,swell, the cell-swelling-induced chloride current and ICln, the nucleotide-sensitive chloride current induced by expression of mammalian pICln in Xenopus oocytes, have led to models which identify pICln either as the volume-sensitive chloride channel or as a cytosolic regulator thereof. 2. To investigate critically the relationship between ICl,swell and pICln two-microelectrode voltage clamp experiments were performed on Xenopus oocytes in which either human pICln was expressed or endogenous ICl,swell was activated. 3. Several criteria that clearly differentiated ICln from ICl,swell were detected. Outward rectification and the discrimination between NO3- and Cl- were more pronounced for ICln. Cyclamate blocked ICln but not ICl,swell. In contrast to ICl,swell, inactivation kinetics of ICln were pH independent and extracellular cAMP blocked only the outward ICln component. Finally, ICln was readily expressed in collagenase-defolliculated oocytes and was not modulated by extracellular hypotonicity, whereas ICl,swell could only be triggered in follicle-enclosed or manually defolliculated oocytes. 4. We therefore conclude that ICln and ICl,swell are two different chloride currents. Consequently, any model which invokes a crucial role for pICln in ICl,swell should be critically reviewed.
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PMID:The chloride current induced by expression of the protein pICln in Xenopus oocytes differs from the endogenous volume-sensitive chloride current. 888 55

Rat submandibular glands have been digested with collagenase P and a crude cellular suspension has been prepared. The [Ca2+]i and the pHi of these cells have been measured using fluorescent probes extracellular ATP increases the [Ca2+]i. At low concentrations ATP binds to a metabotropic receptor coupled to the mobilization of intracellular calcium stores. At high concentrations ATP activates a ionotropic receptor coupled to a non-specific cation channel permeant to calcium, sodium or zinc. The increase of the [Ca2+]i in response to ATP opens an anion permeability leading to a drop of the pHi. The acidification in response to ATP is potentiated by the removal of extracellular chloride or by the addition of an inhibitor of chloride channels in the incubation medium. Acetazolamide, an inhibitor of carbonic anhydrase blocks by 30% the intracellular acidosis in response to ATP. It is concluded that anions (among which bicarbonate is only a fraction) leave the cells by a chloride channel. The pHi does not decrease below 6.8 for two reasons: 1) the uptake of sodium by the non-specific cation channel and the ensuing depolarization on one hand and the decrease of the pHi on the other hand reverse the proton-moving force; 2) at low pHi the non-specific cation channel becomes permeable to protons. These results suggest that purinergic agonists are secretagogues. But at the opposite to classical secretagogues which increase the efflux of chloride, purinergic agonists rather increase the permeability to organic anions.
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PMID:[Effect of purinergic agents on ion movement in submaxillary glands]. 949 28

In this paper, membrane current properties of the fully-grown oocytes from toad, Bufo bufo gargarizans, were studied by using two-microelectrode voltage clamp technique. Axion of adult female toad was destroyed, and then ovarian lobes containing oocytes in stage I to VI were removed and incubated in Ca(2+)-free ND96 solution with collagenase (1.5 mg/ml) for 1 h. Subsequently, the oocytes were washed in Ca(2+)-free ND96 solution for 10 min to completely remove the follicular layer. For the experiments only the oocytes in stage V and VI were selected and used during 1 to 5 d. The membrane was depolarized from a holding potential of -80 mV to +60 mV in 10 mV step. It was found that a sustained outward current was elicited by depolarization. Potassium channel blockers (tetraethylammonium chloride, TEA, 10 mmol/L and 4-aminopyridine, 4-AP, 10 mmol/L) reduced the outward current to (23.4+/-0.72)% of the maximum. However, further addition of chloride channel blocker (5-nitro-2, 3-phenypropylamino benzoate, NPPB, 30 micromol/L) could almost completely block the outward current to (2.1+/-0.08)% of the maximum. In the presence of TEA and 4-AP, removal of extracellular Ca(2+) or adding verapamil (40 micromol/L), could also reduce the outward current to (2.2+/-0.04) % and (3.1+/-0.15) % of the maximum, respectively. It is concluded that calcium-dependent chloride channels exist in plasma membrane of Bufo bufo gargarizans oocytes, besides potassium channels.
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PMID:[Calcium-dependent chloride channels in plasma membrane of oocytes from toad, Bufo bufo gargarizans]. 1704 32