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)

Hormone-dependent adenylate cyclase activity was measured separately in the different nephron portions by combining the microdissection of collagenase-treated rabbit kidneys and the use of a single tubule enzyme microassay. The results obtained in the rabbit for vasopressin, parathyroid hormone, calcitonin, and isoproterenol are given and discussed. Each hormone stimulated adenylate cyclase activity in several well-localized segments of tubule according to a highly specific and reproducible pattern. Sharp transitions were generally noted between responsive and unresponsive nephron portions. In the rat kidney, the functional segmentation of the distal convoluted tubule was not as clearly delineated as in the rabbit kidney. Various nephron segments of the rat kidney were observed to contain glucagon-sensitive adenylate cyclase activity. When the results obtained for vasopressin are compared in rabbit, rat, mouse, and human kidneys, species differences are noted with respect to the responsiveness to arginine vasopressin in the medullary portion of thick ascending limbs of Henle's loops. It is concluded that biochemical approaches can be used as a means of investigating problems dealing with kidney physiology very near the cell level.
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PMID:Sites of hormone action in the mammalian nephron. 625 51

Several studies have revealed a variety of interactions between PTH and ACTH. The existence of a significant area of homology in the bioactive regions of the two molecules has been proposed as a possible reason for such interactions. To clarify the relationship, corticosteroidogenic and cAMP accumulative effects of bovine PTH (bPTH 1-84), its amino-terminal fragment (bPTH 1-34), and the amino terminal fragment of human PTH (hPTH 1-34) were compared with ACTH 1-39 by determining their dose-response characteristics in collagenase-dissociated adrenocortical cells from rats. bPTH 1-84 and bPTH 1-34 (10(-8)-10(-5)M) did not alter steroid production of the cells nor did 10(-6)M bPTH 1-34 affect the steroid response curve to ACTH 1-39. However, the degree of steroidogenesis elicited by hPTH 1-34 over the dose range 3.3 X 10(-7)-3.3 X 10(-5)M was the same as that elicited by ACTH 1-39 over the range 10(-11)-10(-9) M. cAMP generation with hPTH 1-34 was maximal at 10(-4) M but the correlation between the steroid and cAMP responses with ACTH 1-39 was noticeably different from that with hPTH 1-34. In experiments with ACTH 6-24 (a competitive inhibitor of ACTH 1-39), both steroid and cAMP responses to hPTH 1-34 were greatly reduced. Oxidized hPTH 1-34 did not elicit any steroid production nor did several other peptide hormones (arginine vasopressin, angiotensin II, calcitonin, insulin, GH) at 10(-5) M. These observations indicate that hPTH 1-34 can exert a direct and specific effect on rat adrenocortical cells revealing the peptide as a full agonist for steroid production in this system. We suggest that it is a combination of sequence homology and conformational structure which permits hPTH 1-34 to interact with, and elicit its response through, the receptor for ACTH 1-39.
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PMID:Corticosteroidogenesis and adenosine 3', 5'- monophosphate production by the amino-terminal (1-34) fragment of human parathyroid hormone in rat adrenocortical cells. 630 60

The effects of arginine vasopressin (AVP) and its nonpressor analogue desamino-8-arginine vasopressin (dDAVP) on immunoreactive prostaglandin E and thromboxane B2 synthesis from endogenous arachidonic acid by epithelial cells isolated from toad urinary bladders were investigated. In epithelial cell suspensions prepared using a collagenase treatment, AVP (5 mU/ml) stimulated prostaglandin E synthesis from 0.27 +/- 0.05 to 0.53 +/- 0.09 pmol . min-1 . mg protein-1 (P less than 0.01, n = 6) and stimulated thromboxane A2 synthesis, as assessed by measurement of its stable metabolite thromboxane B2, from 0.032 +/- 0.004 to 0.054 +/- 0.009 pmol . min-1 . mg protein-1 (P less than 0.02, n = 6). dDAVP (130 nM) also stimulated immunoreactive prostaglandin E and thromboxane B2 synthesis (P less than 0.05, n = 6). In cells prepared by EDTA treatment or scraping, aVP did not alter prostaglandin or thromboxane synthesis. This study demonstrates that AVP and dDAVP stimulate both prostaglandin and thromboxane synthesis in epithelial cells from the toad urinary bladder and suggests that the antidiuretic activity of these peptides is associated with this effect. The results are consistent with previous observations that the synthesis of prostaglandin E and thromboxane by epithelial cells results in a negative and positive modulation, respectively, of the action of AVP on water transport.
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PMID:Vasopressin stimulates prostaglandin and thromboxane synthesis in toad bladder epithelial cells. 681 73

Cortical collecting duct fragments were manually dissected from 6-wk-old Sprague-Dawley rats. The fragments were enzymatically digested (collagenase A) into single cells, washed, and resuspended in serum-free RPMI 1640. Individual cells were examined electrophysiologically using the whole cell patch-clamp technique. Two morphologically distinct cell types were present in the cell suspension. Small round cells that had a capacitance of 7 pF and larger oval cells with a capacitance of 29 pF were consistently observed. Whole cell electrophysiological examination revealed that the small round cells had virtually no plasma membrane ionic conductance, whereas both inward and outward currents were observed in the larger oval-type cells. Also, superfusion of 250 pM arginine vasopressin specifically increased the inward conductance of only the larger cells. The effect could be completely inhibited by 2 microM amiloride or 100 mumol of the Rp diastereomer of 8-(4-chlorophenylthio)-adenosine 3',5'-cyclic monophosphate (a specific adenosine 3',5'-cyclic monophosphate inhibitor). These findings are consistent with the hypothesis that the larger cells are principal cells and the smaller cells are intercalated cells and directly demonstrate that an amiloride-sensitive whole cell conductance is readily observable in freshly isolated cortical collecting duct cells. Thus the whole cell configuration of the patch-clamp technique appears to be well suited for assessing cellular mechanisms that regulate the ionic conductances of cortical collecting duct cells.
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PMID:Whole cell sodium conductance of principal cells freshly isolated from rat cortical collecting duct. 757 11

We describe, for the first time, the development of a technique for a long-term selective culture of endocrine (PE) cells from the lungs of normal animals. Epithelial cells were isolated from 1-day-old hamster lungs through mechanical and enzymatic dissociation with collagenase type II. Cells were then cultured in HITES medium which contained RPMI 1640, hydrocortisone, insulin, transferrin, estradiol, sodium selenite, and supplemented with 5% fetal bovine serum (FBS), or medium which contained HITES medium supplemented with bovine serum albumin, phosphoethanolamine, arginine vasopressin, bombesin, and 2% FBS (9N). HITES medium, originally developed for establishment and long-term culture of human small cell lung cancer (SCLC) cell lines, allowed propagation of normal hamster PE cells up to 12 months as a mixed floating-attached cell culture. No difference was noted in the results using HITES or 9N. By 3 months, 80% of the cultured cells contained characteristic dense-core (endocrine type) granules. The cultured PE cells also expressed creatine kinase brain isoenzyme, and general NE markers including neuron specific enolase, and amine handling enzyme activity within the range of SCLC cell lines. Moreover, cultured PE cells contained and secreted immunoreactive calcitonin (iCT) which had a molecular profile similar to that of intact hamster lung. This long-term culture technique should markedly assist in elucidating the role of PE cells in health and disease.
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PMID:Long-term selective culture of hamster pulmonary endocrine cells. 838 31

The multifactorial control of ACTH is well established. We wished to establish and characterize an in-vitro perifusion system, using equine anterior pituitary cells and physiological concentrations of secretagogues, to investigate factors which affect the dynamics of ACTH secretion. Anterior pituitary tissue was divided for dispersion into cells with collagenase, trypsin or dispase, or by mechanical dispersion. After dispersal followed by 18-h incubation, cells were perifused and the ACTH response to 10-min pulses of arginine vasopressin (AVP; 100 nmol/l), corticotrophin-releasing hormone (CRH; 0.01 nmol/l), and AVP (100 nmol/l) plus CRH (0.01 nmol/l) determined. ACTH responses to these secretagogues were lower (P < 0.05) in cells prepared using the enzymes dispase and trypsin than with the enzyme collagenase. Cells prepared by mechanical methods were not responsive. Collagenase-prepared cells were used in subsequent experiments. In dose-response studies (10-min pulse length), a steep CRH-ACTH dose-response curve was obtained with the minimum effective concentration of CRH between 0.001 and 0.01 nmol/l, and a maximum effective concentration of 1.0 nmol/l. A less steep AVP-ACTH dose-response curve was obtained with a minimum effective concentration of AVP between 0.5 and 5 nmol/l, and no plateau in response up to 5000 nmol AVP/l. Increasing the incubation time between cell preparation and stimulation with AVP from 18 h to 90 h significantly (P < 0.01) increased the ACTH response. Repeated stimulation by AVP (100 nmol/l) or CRH (0.01 nmol/l) (5-min pulses every 30 min for 23 pulses) produced ACTH responses which decreased in an approximately exponential curve with time. When AVP and CRH were given at physiological concentrations, pulse lengths and pulse frequency, the ACTH response to repeated 1-min pulses of AVP, measured as height above basal secretion, was potentiated by the addition of CRH (1, 2.5, 5, 10 and 20 pmol/l) as a constant perifusion at all AVP concentrations tested (1 nmol AVP/l, P < 0.02; 10 nmol AVP/l, P < 0.0005; 25 nmol AVP/l, P < 0.0005). During the 1-min AVP pulse, the AVP concentration at the level of the cells was 30% of the expected concentration. Potentiation was increased both by increasing AVP concentration (P < 0.00005) and by increasing CRH concentration (P < 0.00005) up to 5 pmol CRH/l. The ACTH height response to repeated AVP stimulation significantly (P = 0.034) decreased with time, independent of CRH and AVP concentration. There was a significant (P = 0.014) decrease in ACTH response to CRH infusion with time, independent of CRH concentration.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Factors affecting ACTH release from perifused equine anterior pituitary cells. 839 18

Calcium signaling mechanisms were examined in vessel segments and dispersed single smooth muscle cells (SMC) of interlobular arteries and afferent arterioles (< 50 microns diameter) from the rat kidney. These resistance vessels were isolated from rat kidneys, using an iron oxide-sieving technique with subsequent collagenase digestion. Individual cells were identified by their characteristic oval appearance and positive staining for smooth muscle-specific alpha-actin and heavy chain myosin SM-1 and SM-2. Cytosolic calcium concentration ([Ca2+]i) was measured using fura 2 ratiometric fluorescence at 340 and 380 nm wavelength with a microscope-based photometer. Angiotensin II (ANG II) and arginine vasopressin (AVP), at concentrations of 10(-10)-10(-6) M, produced dose-dependent increases in [Ca2+]i; maximum increases were 221 +/- 49 nM for ANG II and 237 +/- 49 nM for AVP. The temporal response patterns for both agonists were characterized by a square-shaped, immediate step increase in [Ca2+]i to a near maximum level that was maintained through the recording period of 150-200 s. Responses of individual dispersed SMC and short vessel segments were similar. Losartan antagonized the action of ANG II, indicating mediation by AT1 receptors on preglomerular arteriolar SMC. The V1-selective antagonist [d(CH2)5Tyr(Me)2Tyr(NH2)9]AVP completely inhibited AVP-induced [Ca2+]i changes. The importance of calcium entry in hormone-induced changes in [Ca2+]i was demonstrated by the finding that neither ANG II nor AVP elicited a [Ca2+]i response in media rendered nominally calcium free by addition of ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid. Calcium entry occurred primarily through L-type, voltage-gated calcium channels as the dihydropyridine, nifedipine, completely prevented or reversed [Ca2+]i changes normally elicited by either hormone. Our results provide new information about the similarity of calcium signaling in single SMC and short segments freshly isolated from renal interlobular arteries and afferent arterioles. The observations indicate that AT1 and V1 receptors are coupled to signal transduction pathways leading to rapid changes in [Ca2+]i. Calcium mobilization appears to play a minor to nonexistent role under the experimental conditions. The predominant mechanism involves calcium entry through dihydropyridine-sensitive, voltage-gated calcium channels in single SMC from these resistance vessels.
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PMID:ANG II and vasopressin stimulate calcium entry in dispersed smooth muscle cells of preglomerular arterioles. 953 Feb 66

In the present study, adrenocorticotropic hormone (ACTH) release and intracellular calcium ([Ca(2+)](i)) increase induced by arginine vasopressin (AVP) were characterized in collagenase-dispersed and 3-day cultured rat anterior pituitary cells. AVP and the selective vasopressin V(1b) receptor agonist, [1-deamino-4-cyclohexylalanine]AVP (d[Cha(4)]AVP) induced ACTH release with nanomolar potencies in both cell preparations, and produced a maximal stimulation that was about 1.5 fold greater in the 3-day cultured cells, indicating that the vasopressin V(1b) receptor-ACTH release pathway is enhanced over time in culture. In dispersed cells, AVP, oxytocin and d[Cha(4)]AVP induced [Ca(2+)](i) increases with nanomolar potencies. The selective vasopressin V(1a) receptors antagonist, SR49059 (100 nM), together with the selective oxytocin receptors antagonist (d(CH(2))(5)(1)Tyr(Me)(2),Thr(4),Orn(8),Tyr-NH(2)(9)-vasotocin (100 nM), inhibited the maximal AVP response by ~70%, without affecting the response to d[Cha(4)]AVP, suggesting that the V(1b) receptor was only partially responsible for the AVP-induced [Ca(2+)](i) increase. In contrast, in 3-day cultures, AVP induced an increase in [Ca(2+)](i), while oxytocin and d[Cha(4)]AVP did not. The response to AVP was completely antagonized by SR49059, whereas the vasopressin V(1b) receptor antagonists, SSR149415 and (d(CH(2))(5)(1)Tyr(Me)(2),Thr(4),Orn(8),Tyr-NH(2)(9))-vasotocin had no effect, indicating that the [Ca(2+)](i) increase was mediated exclusively by vasopressin V(1a) receptors. In conclusion, the enhancement of vasopressin V(1b) receptor-mediated ACTH release and the lack of a detectable vasopressin V(1b) receptor coupling to [Ca(2+)](i) increase in cultured cells suggests the activation of a different/additional signaling pathway in the molecular mechanism of ACTH release.
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PMID:Distinct receptor subtypes mediate arginine vasopressin-dependent ACTH release and intracellular calcium mobilization in rat pituitary cells. 2228 55


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