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: UNIPROT:P01185 (vasopressin)
23,126 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Adenylate cyclase sensitivity to neurohypophyseal hormones was investigated in isolated glomeruli and in nephron segments microdissected from collagenase-treated kidneys of Rana ridibunda. Vasotocin treatment increased adenylate cyclase activity in glomeruli and in collecting ducts and did not modify it in proximal convoluted tubules and in early and late distal tubules. In glomeruli, the hormonal stimulation resulted mainly in a decrease in the Km value for adenylate cyclase, which means a higher affinity for substrate (ATP) to the enzyme, whereas the response to forskolin was accounted for by increases both in affinity for substrate and in maximal adenylate cyclase velocity. The homologous neurohypophyseal hormones stimulated frog glomerular adenylate cyclase with the following rank order of affinities: hydrin 1 > or = AVT = AVP > or = hydrin 2 > OT > or = mesotocin > isotocin; structural analogs dDAVP, VDAVP, dVDAVP, and [Phe2,Orn8]VT had weak agonistic properties, [Thr4,Gly7]OT was inactive, and the antagonists OVTA, d(CH2)5Tyr(Et)2VAVP, and des-Gly9-d(CH2)5Tyr(Et)2VAVP inhibited hormone-induced enzyme activation with similar apparent inhibition constants. The vasotocin receptors triggering adenylate cyclase stimulation in frog glomeruli differ pharmacologically from V2 vasopressin receptors of mammalian kidneys and may also differ from V2-like vasotocin receptors of amphibian skin and urinary bladder.
...
PMID:Vasotocin-sensitive adenylate cyclase in frog glomeruli. 778 59

Vasotocin receptors were investigated in glomeruli and nephron segments microdissected from collagenase-treated kidneys of Rana ridibunda, using [d(CH2)5Tyr(Me)2,Thr4,Orn8,125I-Tyr-NH2(9)]vasotocin (125I-OVTA) as a radioligand. Specific 125I-OVTA binding sites were found only in glomeruli and not in all tubule segments tested. Glomerular receptors exhibited the following stereospecificity for recognition of vasotocin analogues: Tyr-NH2(9)-LA-V1a > 125I-OVTA > arginine vasotocin (AVT) > or = [d(CH2)5Tyr-(Me)2]AVP > OVTA > or = [Phe2,Orn8]VT > oxytocin (OT) > or = [d(CH2)5-Sar7]AVP > desGly9[d(CH2)5Tyr(Et)2]VAVP > or = [d(CH2)5Tyr(Et)2]VAVP > AVP > [1-desamino-8-D-arginine]vasopressin (DDAVP) > [Thr4,Gly7]OT. In addition, vasotocin enhanced [3H]inositol phosphate production in sieved glomeruli labeled with myo-[3H]inositol; the rank order of structural vasotocin analogues for stimulation of phosphoinositidase C was [Phe2,Orn8]VT > AVT > OT > AVP > DDAVP, whereas [Thr4,Gly7]OT was almost inactive, and the rank order of antagonists for inhibition of hormone-induced enzyme activation was Tyr-NH2(9)-LA-V1a > [d(CH2)5Tyr(Me)2]AVP = OVTA > [d(CH2)5Sar7]AVP > [d(CH2)5Tyr(Et)2]VAVP > or = desGly9[d(CH2)5Tyr(Et)2]VAVP. Results indicate that the 125I-OVTA-labeled binding sites detected in frog glomeruli reveal the pharmacological properties of mammalian V1b-pituitary vasopressin receptors and might be physiological vasotocin receptors involved in phosphoinositidase C stimulation.
...
PMID:Frog glomerular vasotocin receptors resemble mammalian V1b receptors. 797 46

Liver regeneration following partial hepatectomy is significantly impaired in rats with hereditary vasopressin (AVP) deficiency. This suggested that AVP might have a direct effect on cultured rat hepatocytes. Hepatocytes from male Sprague-Dawley rats were isolated using a two-step collagenase perfusion technique and plated at a density of 10(5)/16-mm Primaria plate. After a suitable attachment period, hepatocytes were incubated with minimal essential media, AVP, AVP plus a specific AVP antagonist, or oxytocin. Hepatocyte proliferation was measured by [3H]thymidine incorporation ([3H]Thy) into hepatocyte DNA. AVP (10 nM) increased [3H]Thy significantly (and this effect was blocked by an AVP-specific antagonist (50 nM). Oxytocin had no effect on hepatocyte DNA synthesis. To further investigate the influence of AVP on hepatocyte proliferation, the effect of AVP on transforming growth factor-alpha (TGF-alpha)-stimulated hepatocyte proliferation was also studied. This combination was chosen based on the ability of AVP to inhibit the biologic effects of EGF (a TGF-alpha analog). There was significant attenuation of TGF-alpha (50 nM)-stimulated [3H]Thy in the presence of AVP (10 nM). In summary: (1) AVP stimulates proliferation of cultured rat hepatocytes. (2) The effect of AVP can be significantly abolished by a specific AVP antagonist. (3) The proliferative response of AVP is specific. (4) AVP significantly attenuates TGF-alpha-stimulated hepatocyte hepatic DNA synthesis. Further studies should elucidate the mechanisms for the effects of AVP on hepatic proliferation alone or in combination with other factors.
...
PMID:Vasopressin stimulates DNA synthesis in cultured rat hepatocytes. 799 50

Magnesium transport across the plasma membrane of cardiac and liver cells appears to be under hormonal control. The increase in cytosolic cAMP, following the adrenergic stimulation of both cell types, results in a major Mg2+ efflux from perfused rat hearts or livers and from collagenase-dispersed ventricular myocytes or hepatocytes. By contrast, the activation of protein kinase C by carbachol, vasopressin, phorbol-myristate acetate or diacylglycerol analogs induces Mg2+ accumulation in either of the experimental models. As for the role of intracellular compartments on Mg2+ homeostasis, the cAMP-mediated Mg2+ efflux largely depends on the mobilization of Mg2+ from mitochondria via the mitochondrial adenine nucleotide translocase. By contrast, Mg2+ influx appears to be related to the endo(sarco)plasmic reticulum and its dynamic handling of cytosolic Ca2+.
...
PMID:Cell magnesium transport and homeostasis: role of intracellular compartments. 826 15

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

Preceding studies using the hamster insulinoma cell line, HIT, and isolated rat hepatocytes have shown that two essential components of the Ca2+ signaling pathway, the ATP-dependent Ca2+ store and the store-coupled Ca2+ influx pathway, are both located in microvilli covering the surface of these cells. Microvilli-derived vesicles from both cell types exhibited anion and cation pathways which could be inhibited by anion and cation channel-specific inhibitors. These findings suggested that the microvillar tip compartment forms a space which is freely accessible for external Ca2+, ATP, and IP3. The entry of Ca2+ into the cytoplasm, however, is largely restricted by the microvillar core structure, the dense bundle of actin microfilaments acting as a diffusion barrier between the microvillar tip compartment and the cell body. Moreover, evidence has been presented that F-actin may function as ATP-dependent and IP3-sensitive Ca2+ store that can be emptied by profilin-induced depolymerization or reorganization [K. Lange and U. Brandt (1996) FEBS Lett. 395, 137-142]. Here we demonstrate the tight connection between microvillar shape changes and the activation of the Ca2+ signaling system in isolated rat hepatocytes. Using a combination of scanning electron microscopy (SEM) and fura-2 fluorescence technique, we confirmed a consequence of the "diffusion barrier" concept of Ca2+ signaling: Irrespective of the type of the applied stimulus, activation of the Ca2+ influx pathway is accompanied by changes in the structural organization of microvilli indicative of the loss of their diffusion barrier function. We further show that the cell surfaces of unstimulated hepatocytes isolated by either the collagenase or the EDTA perfusion technique are densely covered with microvilli predominantly of a short and slender type. Beside this rather uniformly shaped type of microvilli, a number of dilated surface protrusions were observed. Under these conditions the cells displayed the well known rather high basal [Ca2+]i of 200-250 nM as repeatedly demonstrated for freshly isolated hepatocytes. However, addition of the serine protease inhibitor, phenylmethanesulfonyl fluoride (PMSF), to the cell suspension immediately after its preparation reduced the basal cytoplasmic Ca2+ level to about 100 nM. Concomitantly, dilated surface protrusions disappeared, and cell surfaces exclusively displayed short, slender microvilli. Activation of the Ca2+ signaling pathway by vasopressin, as well as by the IP3-independent acting Ca2+ store inhibitor, thapsigargin, was accompanied by a conspicuous shortening and dilation of microvilli following the same time courses as the respective increases of [Ca2+]i induced by the effectors. Furthermore, the abundance of the large form of surface protrusions on isolated hepatocytes positively correlated with the size of a cellular Ca2+/Fura-2 compartment which is rapidly depleted from Ca2+ by extracellular EGTA. These findings support the postulated localization of the store-coupled Ca2+ influx pathway in microvilli of HIT cells also for hepatocytes and are in accord with the notion of a cytoskeletal diffusion barrier regulating the flux of external Ca2+ via the microvillar tip region in the cytoplasm.
...
PMID:Activation of calcium signaling in isolated rat hepatocytes is accompanied by shape changes of microvilli. 926 Sep 19

Experiments were conducted to gain insight into mechanisms responsible for exaggerated renal vascular reactivity to ANG II and vasopressin (AVP) in spontaneously hypertensive rats (SHR) during the development of hypertension. Cytosolic calcium concentration ([Ca2+]i) was measured by ratiometric fura 2 fluorescence and a microscope-based photometer. Vascular smooth muscle cells (SMC) from preglomerular arterioles were isolated and dispersed using an iron oxide-sieving method plus collagenase treatment. ANG II and AVP produced rapid and sustained increases in [Ca2+]i. ANG II elicited similar dose-dependent increases in [Ca2+]i in SMC from SHR and Wistar-Kyoto rats (WKY). In contrast, AVP caused almost twofold larger responses in afferent arteriolar SMC from SHR. ANG II effects were inhibited by the AT1 receptor antagonist losartan. AVP action was blocked by the V1 receptor antagonist [d(CH2)5,Tyr(NH2)9]AVP. In SMC pretreated with nifedipine, neither ANG II nor AVP elicited [Ca2+]i responses. Poststimulation nifedipine reversed elevated [Ca2+]i to basal levels. Short-term reductions in external [Ca2+]i (EGTA) mimicked the nifedipine effects. Our study shows that AT1 and V1 receptors stimulate [Ca2+]i by a common mechanism characterized by preferential action on voltage-gated L-type channels sensitive to dihydropyridines. Calcium signaling elicited by AT1 receptors does not differ between SHR and WKY; thus the in vivo exaggerated reactivity may be dependent on interactions with other cell types, e. g., endothelium. In contrast, AVP produced larger changes in [Ca2+]i in arteriolar SMC from SHR, and such direct effects can account for the exaggerated renal blood flow responses.
...
PMID:Exaggerated Ca2+ signaling in preglomerular arteriolar smooth muscle cells of genetically hypertensive rats. 995 Sep 57

The studies presented here were performed to determine the effect of agonist stimulation on the cytosolic free Ca2+ concentration ([Ca2+]i) in single smooth muscle cells, freshly isolated from afferent arterioles and interlobular arteries averaging between 10 to 40 microns in diameter. Microvessels were obtained from male Sprague-Dawley rats using an iron oxide collection technique followed by collagenase digestion. Freshly isolated microvascular smooth muscle cells (MVSMC) were loaded with fura 2 and studied using fluorescence photometry techniques. The resting [Ca2+]i averaged 67 +/- 3 nM (N = 82 cells). Increasing the extracellular K+ concentration significantly increased [Ca2+]i dose-dependently (P < 0.05). Involvement of extracellular Ca2+ in the response to KCl-induced depolarization was also evaluated. Resting [Ca2+]i increased approximately 132% from 40 +/- 5 nM to 93 +/- 26 nM in response to 90 mM extracellular KCl. This change was abolished in nominally Ca(2+)-free conditions and markedly attenuated by diltiazem. Inhibition of K+ channels with charybdotoxin or tetraethylammonium chloride produced a modest transient increase in [Ca2+]i during the response to 30 mM K+ and had no detectable effect on responses to 90 mM K+. Studies were also performed to establish whether freshly isolated renal MVSMC exhibit appropriate responses to receptor-dependent physiological agonists. Angiotensin II (100 nM) increased cell Ca2+ from 97 +/- 10 nM to 265 +/- 47 nM (N = 12 cells). Similarly, 100 microM ATP increased MVSMC [Ca2+]i from a control level of 71 +/- 14 nM to 251 +/- 47 nM (N = 11 cells). Norepinephrine administration caused [Ca2+]i to increase from 63 +/- 4 nM to 212 +/- 47 nM (N = six cells), and vasopressin increased [Ca2+]i from 86 +/- 10 nM to 352 +/- 79 nM (N = five cells). These data demonstrate that receptor-dependent and -independent vasoconstrictor agonists increase [Ca2+]i in MVSMC, freshly isolated from rat preglomerular vessels. Furthermore, the ability to measure [Ca2+]i in responses to physiological stimuli in these single cells permits investigation of signal transduction mechanisms involved in regulating renal microvascular resistance.
...
PMID:Agonist-induced calcium regulation in freshly isolated renal microvascular smooth muscle cells. 1049 86

We describe a simple method for obtaining functionally and morphologically intact primary cultures of cells from the medullary thick ascending limb of rabbit kidneys. After digesting dissected fragments of the inner stripe of the outer medulla with collagenase, a suspension of tubule fragments is obtained, the vast majority of which are medullary thick ascending limb (MTAL) segments. These are identified individually by their morphological appearance and large amounts are collected with a micropipette mounted on a micromanipulator. This ensures maximal homogeneity of the starting material. Monolayers of cells grow out of these MTAL segments after seeding them onto collagen-coated, permeable filter supports. During the week following confluence, the cultures exhibit an apical side-positive transepithelial potential difference. Electron microscopic examination shows a monolayer of polarised cells with characteristics of distal tubular cells. The primary cultures express Tamm-Horsfall protein at their apical surface. Additional evidence for their differentiation and polarisation is the net ammonium influx, which occurs at very high rates across the apical membrane and is much slower across the basolateral membrane, as judged by measurements of intracellular pH. Adenosine 3',5'-cyclic monophosphate (cAMP) production is stimulated by arginine-vasopressin, calcitonin or isoproterenol (all 1 micromol/l). Intracellular calcium signalling is observed after stimulation with 1 micromol/l adenosine, adenosine 5'-triphosphate (ATP) and bradykinin. In addition, we compared these characteristics with those of TALH-SVE cell monolayers, an established immortalised cell line of the same origin.
...
PMID:A simple method for obtaining functionally and morphologically intact primary cultures of the medullary thick ascending limb of Henle's loop (MTAL) from rabbit kidneys. 1095 49

A collagenase-based dissociation technique has been developed to routinely establish monolayer cultures of freshly isolated porcine vas deferens epithelium. Cells isolated from each tissue are transferred to 25-cm(2) tissue culture flasks and grown in a standard cell culture medium. Flasks reach confluency in 3-4 days, and cells are subsequently seeded onto permeable supports. Cultured cells display a monolayer cobblestone appearance and are immunoreactive to anti-ZO-1 and anti-cytokeratin antibodies. Electron microscopy is employed to demonstrate the presence of junctional complexes and microvilli. When evaluated in modified Ussing chambers, cultured monolayers exhibit a basal lumen negative potential difference, high electrical resistance (>1,000 Omega. cm(2)), and respond to norepinephrine, vasopressin, ATP, adenosine, and histamine, with changes in short-circuit current indicative of anion secretion. Responses are significantly attenuated in Cl(-)- and/or HCO-free solutions. Attempts to further optimize culture conditions have shown that chronic exposure to insulin increases proliferation rates. Thus the culture method described will reliably produce viable neurotransmitter-responsive cell monolayers that will allow for the characterization of vas deferens epithelial function and associated control mechanisms.
...
PMID:Neurotransmitter-stimulated ion transport by cultured porcine vas deferens epithelium. 1150 4


<< Previous 1 2 3 4 5 6 Next >>

---