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)

The intravenous administration of glucagon to anesthetized rats resulted within 5 min in a 20% drop in the hepatic phosphorylase phosphatase activity, as measured in a post-mitochondrial supernatant at low dilution, but it did not affect the activity of glycogensynthase phosphatase. On the other hand, the injection of insulin plus glucose caused increases by about 35% in both phosphatase activities. Upon subcellular fractionation these effects were recovered in the cytosol, but not in the glycogen/microsomal fraction. However, activity changes in the latter fraction were observed after recombination with the liver cytosol from a hormone-treated animal. Preincubation of the liver cytosol with modulator protein (a specific inhibitor of type-1 protein phosphatases) cancelled the activity changes induced by insulin plus glucose. No hormonal effects on hepatic protein phosphatase activities were observed when the fractions were either diluted an additional 10-fold or pretreated with trypsin. An acute hormonal regulation of protein phosphatases could also be demonstrated in the perfused liver. When added to the perfusion medium, glucose as well as insulin increased the cytosolic protein phosphatase activities by about 25%. Their effect was additive, irrespective of the order of addition. On the other hand, the addition of glucagon and/or vasopressin resulted in a 20% drop in the phosphorylase phosphatase activity. The presence of glucagon did not interfere with the effectiveness of insulin, and vice versa. The changes in the phosphorylase phosphatase activities induced by glucagon, insulin, and glucose represented changes in the Vmax only. We propose that the acute control of the hepatic glycogen synthase phosphatase and phosphorylase phosphatase activities is mediated by transferable, cytosolic effector(s).
...
PMID:Acute regulation of hepatic protein phosphatases by glucagon, insulin, and glucose. 284 53

A single class of high affinity, low capacity, specific binding sites for [3H]arginine8 vasopressin (AVP) has been characterized in a plasma membrane-enriched microsomal fraction of the rat liver. Specific binding was saturable, linear with protein concentration, reversible, and 40-65% of the total binding. Binding at 25 C achieved a plateau after 30 min of incubation, whereas at 4 C, equilibrium was reached more slowly, and the level of binding was reduced. The presence of magnesium (Mg2+) in the assay medium enhanced the affinity of specific binding, while calcium and higher levels of sodium and potassium decreased binding. Scatchard analysis of binding in the presence of Mg2+ (5 mM) revealed an apparent mean +/- SE equilibrium dissociation constant (Kd) of 0.29 +/- 0.08 nM, with a maximal site density (Bmax) of 150.4 +/- 25.0 fmol/mg; in contrast, the Kd was 1.93 +/- 0.33 nM and the Bmax was 113.4 +/- 40.0 fmol/mg in the absence of Mg2+. No significant differences in Kd and Bmax were observed among membrane fractions derived from spontaneously hypertensive rats, Wistar-Kyoto rats, Long-Evans rats, and Brattleboro rats. Plasma levels of AVP were similar in spontaneously hypertensive, Wistar-Kyoto, and Long-Evans rats, but AVP was not detectable in the plasma from DI rats. Competitive inhibition of specific [3H]AVP binding by unlabeled AVP and related peptides showed the following Ki values: AVP, 0.19 nM; LVP, 1.7 nM; oxytocin, 41.4 nM; desamino AVP, 0.38 nM; [1-(beta-mercapto-beta, beta-cyclopentamethylene propionic acid) 4-Val,8-D-Arg] VP2-(O-methyl)tyrosine]AVP, 1.8 nM; desglycinamide AVP, 2.2 microM. The neuropeptide metabolite of AVP [[pGlu4,Cyt6] AVP-(4-9)], angiotensin II, and other unrelated peptides did not displace [3H]AVP, demonstrating the specificity of AVP and its related biologically active peptides for this binding site. Moreover, the rank order of potency for displacement of [3H]AVP binding by these various peptides parallels their reported glycogenolytic activity in liver and/or their agonistic or antagonistic potency in vascular smooth muscle. Finally, the Mg2+-induced increase in the affinity of [3H]AVP for this liver binding site is similar to the reported effect of Mg2+ on the contractile responses of vascular smooth muscle to AVP (i.e. increased affinity). The results are consistent with the interpretation that the high affinity receptor site characterized in rat liver microsomes is of the V1 type.
...
PMID:Characterization of a specific, high affinity [3H]arginine8 vasopressin-binding site on liver microsomes from different strains of rat and the role of magnesium. 300 5

Osmotic water permeability of the apical membrane of toad urinary epithelium is increased greatly by vasopressin (VP) and is associated with exocytic addition of granules and aggrephores at the apical surface. To determine the physiological role of granule exocytosis, we measured the osmotic water permeability and membrane fluidity of isolated granules, surface membranes and microsomes prepared from toad bladder in the presence and absence of VP. Pf was measured by stopped-flow light scattering and membrane fluidity was examined by diphenylhexatriene (DPH) fluorescence anisotropy. In response to a 75 mM inward sucrose gradient, granule size decreased with a single exponential time constant of 2.3 +/- 0.1 sec (SEM, seven preparations, 23 degrees C), corresponding to a Pf of 5 x 10(-4) cm/sec; the activation energy (Ea) for Pf was 17.6 +/- 0.8 kcal/mole. Under the same conditions, the volume of surface membrane vesicles decreased biexponentially with time constants of 0.13 and 1.9 sec; the fast component comprised approximately 70% of the signal. Granule, surface membrane and microsome time constants were unaffected by VP. However, in surface membranes, there was a small decrease (6 +/- 2%) in the fraction of surface membranes with fast time constant. DPH anisotropies were 0.253 (granules), 0.224 (surface membranes) and 0.190 (microsomes), and were unaffected by VP. We conclude: (1) granules have among the lowest water permeabilities of biological membranes, (2) granule water permeability is not altered by bladder pretreatment with VP, (3) granule membrane fluidity is remarkably lower than that of surface and microsomal membranes, and (4) rapid water transport occurs in surface membrane vesicles. The unique physical properties of the granule suggests that apical exocytic addition of granule membrane may be responsible for the low water permeability of the unstimulated apical membrane.
...
PMID:Very low osmotic water permeability and membrane fluidity in isolated toad bladder granules. 314 39

Arginine-vasopressin (AVP) has been implicated as a putative central neurotransmitter or neuromodulator in some brain functions. This study demonstrates binding of [3H]AVP to rat brain homogenates that is pH and temperature dependent, is saturable (Kd = 0.77 nM, Bmax = 0.374 pmol/mg) and reversible. A number of AVP analogues competitively displaced the [3H]AVP binding, indicating that central AVP binding sites may have a resemblance to the peripheral (V1) AVP vasopressor receptor. Homogenate binding occurred predominantly in the microsomal fraction (P3) of the hypothalamus while in the hippocampus and septum binding was predominantly in the synaptosomal fraction (P2). Autoradiographic methods showed displaceable [3H]AVP binding in the lateral septum, amygdala, supraoptic, paraventricular and suprachiasmatic nuclei of the hypothalamus supporting the results of homogenate binding in preparations of these regions.
...
PMID:[3H]arginine vasopressin binding to rat brain: a homogenate and autoradiographic study. 337 Apr 87

Vasoactive peptides contain a high proportion of proline residues which make them resistant to hydrolysis by many peptidases. However, post proline cleaving enzyme (PPCE; EC 3.4.21.26), a proline specific endopeptidase which specifically hydrolyzes internal peptide bonds on the carboxyl side of proline residues, has been shown to inactivate numerous vasoactive peptides including angiotensins, kinins, substance P, vasopressin and oxytocin. In order to determine whether PPCE could be involved in vascular metabolism of vasoactive peptides, we carried out localization and characterization studies of PPCE-like activity in hog aorta and mesenteric artery. PPCE was assayed fluorometrically at pH 7.0 using the specific PPCE substrate CBZ-Gly-Pro-4-methyl-coumarinylamide. The subcellular distribution of vascular PPCE was essentially the same as that of the cytosolic marker enzyme lactic dehydrogenase (LDH). PPCE was enriched six-fold in the cytosolic fraction (11.4 +/- 2.7 units/mg) and unlike the plasma membrane-bound proline specific exopeptidase dipeptidyl-(amino)peptidase IV (DAP IV; EC 3.4.14.5), little or no activity could be detected in the microsomal or plasma membrane fractions. Similar to PPCE characterized from other sites, vascular PPCE was stabilized and activated by dithiothreitol and EDTA, and inhibited by DFP, p-chloromercuriphenyl sulfonic acid, L-1-tosylamido-2-phenylethylchloromethyl ketone, Cu++, Ca++, and Zn++. Vascular PPCE was unaffected by inhibitors of trypsin and kallikrein (Aprotinin, ABTI), aminopeptidase M (bestatin, amastatin), neutral endopeptidase (phosphoramidon), angiotensin I converting enzyme (captopril) or carboxypeptidase N (MERGETPA). These data demonstrate that PPCE is present in vascular endothelium and/or smooth muscle.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Vascular, post proline cleaving enzyme: metabolism of vasoactive peptides. 354 18

Microsomal preparations from the stalk median eminence of female rats are shown to contain an enzymic activity that is responsible for the formation of MSH-release-inhibiting factor (MSH-R-IF). The amount of this activity remains constant throughout the estrous cycle. The corresponding mitochondrial preparations from the stalk median eminence contain another enzymic principle, estrous cycle-dependent, which competes with the enzyme present in the microsomal preparation for the same "substrate", and can thereby prevent the formation of MSH-R-IF. Several neurohypophyseal hormones, analogs, and peptide intermediates have been tested for their intrinsic MSH-R-IF activity and for their ability to be transformed into MSH-R-IF by incubation with microsomal preparations of stalk median eminence from male rats; it is concluded that the enzyme responsible for the formation of MSH-R-IF is an exopeptidase and that the release-inhibiting factor itself is a tripeptide. Oxytocin is converted by the incubation to (L)-prolyl-(L)-leucylglycinamide; nanogram amounts of this tripeptide inhibit the release of MSH from the pituitary both in vivo and in vitro.
...
PMID:Regulation of formation and proposed structure of the factor inhibiting the release of melanocyte-stimulating hormone. 528 31

Direct binding of 125I-Tyr8-bradykinin to a microsomal fraction prepared from rat uterine smooth muscle, showed an apparent dissociation constant (KD) at 29 degrees C of 5.0 X 10(-10) M calculated from kinetic studies and 6.6 X 10(-10) M from Scatchard plot analysis. The binding of 125I-Tyr8-bradykinin was reversible and saturable, and demonstrated high specificity for Tyr8-bradykinin, bradykinin and Lys-bradykinin, but was not displaced by unrelated peptides angiotensin I, angiotensin II, Arg8-vasopressin and oxytocin. The binding sites were copurified by differential centrifugation and on a discontinuous sucrose density gradient with 5'-nucleotidase activity, a plasma membrane marker enzyme. Prolonged intravenous infusion of bradykinin (5 nmol/h for 2 days) induced a 20% decrease in the number of bradykinin binding sites without a change in the equilibrium dissociation constant. The present results demonstrate that receptors mediating the effect of bradykinin on rat uterine smooth muscle are situated on plasma membranes and the regulation of the receptors is in part under the control of endogenous bradykinin levels.
...
PMID:Bradykinin receptors in rat uterine smooth muscle: studies using radiolabeled ligand binding. 615 Dec 67

Previous studies have shown that hypertonic mannitol or NaCl increases the release of [3H]arachidonate and immunoreactive prostaglandin E in inner medullary slices incubated in Ca2+-free media containing EGTA. By contrast, the stimulation of these parameters by ionophore A23187 and by arginine-vasopressin are abolished in Ca2+-free media plus EGTA. In the present study, the effects of Ca2+ deprivation and the intracellular Ca2+ antagonist TMB-8 [8-N,N-diethylamino)octyl-3,4,5 -trimethoxybenzoate-HCl) were further examined to assess the Ca2+ dependence of the actions of different stimuli of prostaglandin E synthesis in rat renal inner medulla. Ca2+-free media without EGTA abolished increases in [3H]arachidonate and immunoreactive prostaglandin E release induced by ionophore A23187, but not those induced by arginine-vasopressin, suggesting that different pools of Ca2+ subserve expression of the actions of these two stimuli. At low concentrations, TMB-8 (10-25 microM) inhibited increases in [3H]arachidonate and immunoreactive prostaglandin E release induced by arginine-vasopressin, but did not influence effects of Ca2+ plus ionophore A23187 or hypertonicity on these parameters. At higher concentrations (100-500 microM), TMB-8 suppressed effects of ionophore A23187, hyperosmolar NaCl and mannitol on immunoreactive prostaglandin E and [3H]arachidonate release from slices. The effects of a sub-optimal inhibitory concentration of TMB-8 on ionophore A23187 actions were overcome by increasing Ca2+ in the media from 1.5 to 5 mM. Ca2+ deprivation, or concentrations of EGTA or TMB-8, that were effective in suppressing increases in immunoreactive prostaglandin E induced by ionophore A23187, arginine-vasopressin or hypertonicity, did not modify increases in immunoreactive prostaglandin E induced by exogenous arachidonate. Moreover, in microsomal fractions of inner medulla, TMB-8 suppressed Ca2+-dependent increases in phospholipase A2 and C activities, an effect which was competitive with Ca2+. Thus, Ca2+ deprivation and TMB-8 act at a step in the immunoreactive prostaglandin E synthetic pathway proximal to cyclooxygenase activity, and probably at the level of Ca2+-dependent acyl hydrolase activity. The results with TMB-8 indicate that an intracellular pool of Ca2+ is involved in expression of the actions of hypertonicity to increase [3H]arachidonate release and immunoreactive prostaglandin E in inner medulla.
...
PMID:Calcium dependence of the stimulatory action of hypertonicity on renal medullary prostaglandin synthesis. 623 60

The present study investigated whether specific [3H]oxytocin binding sites previously demonstrated in estrogen-dominated rabbit uterus have properties expected of physiologic receptors coupled to uterine contraction. Microsomal membranes from estrogen-dominated rabbit uterus were found to contain high-affinity specific oxytocin binding sites with Kd = 2-3 nM. These sites were predominantly myometrial in locus. Specific oxytocin binding exhibited a pH optimum between 7.5 and 8.0. Mg2+ or Mn2+ was necessary for maximal specific [3H]oxytocin binding; in contrast, Ca2+ at submillimolar concentrations inhibited specific binding. Oxytocin binding sites were not detectable in microsomal membranes isolated from progesterone-dominated rabbit uterus. Relative binding and uterotonic activities of 10 synthetic neurohypophyseal hormone analogues were determined in estrogen-dominated rabbit uterus. A qualitative correlation was observed between binding and uterotonic responses. Angiotensin II and insulin did not compete with [3H]oxytocin for uterine binding sites. It is concluded that the specific high affinity [3H]oxytocin binding sites demonstrated in estrogen-dominated rabbit uterus have the selectivity for neurohypophyseal hormone analogues expected for physiologic receptors coupled to uterine contraction.
...
PMID:Oxytocin receptors coupled to uterine contraction in estrogen-dominated rabbits. 624 2

Basal-lateral membranes were separated in a self-orienting Percoll (modified colloidal silica) gradient from a heavy microsomal membrane fraction by centrifugation at 48,000g for 0.5 h. The (Na+--K+)-ATPase activity as a marker enzyme for the basal-lateral plasma membrane was 20-fold enriched by this procedure. The adenylate-cyclase activity measured in the basal-lateral membrane fraction was stimulated 6-fold by parathyrin and only up to 1.5-fold by arginine-vasopressin, calcitonin, or isoproterenol. The yield of basal-lateral plasma membranes was 5 to 10 percent of the amount initially present in the homogenate. The method is also applicable to the pig kidney.
...
PMID:A simple isolation method for basal-lateral plasma membranes from rat kidney cortex. 626 Oct 79


<< Previous 1 2 3 4 5 Next >>

---