Intravesicular Sodium Research Articles

Intravesicular administration of sodium hyaluronate ameliorates the inflammation and cell proliferation of cystitis cystica et glandularis involving interleukin-6/JAK2/Stat3 signaling pathway

Cystitis cystica et glandularis (CCEG) is a chronic cystitis that causes extreme agony in affected patients. However, there are lack of effective conservative treatments. In this study, it is evident that intravesicular sodium hyaluronate (SH) therapy significantly improved the clinical symptoms of CCEG patients and ameliorated the bladder mucosal inflammation and cell proliferation characteristics of the disease. Immunohistochemical staining showed that the staining intensities of hyaluronidase (HYAL 1/2), CD44, IL-6 and phosphorylated signal transducer and activator of transcription 3 (p-Stat3) in bladder mucosal tissue were significantly increased in CCEG patients compared with control patients and that intravesicular SH treatment suppressed these protein expression. We established a CCEG rat model by treating rats with E. coli intravesicularly, and we found that HYAL 1/2 and CD44 expression levels were significantly increased in the E. coli group compared with the NC group. Activation of the IL-6/JAK2/Stat3 pathway and the expression levels of the downstream pro-apoptotic proteins Mcl-1 and Bcl-xL were also significantly increased in the E. coli group compared with the NC group. The above changes were significantly mitigated by intravesicular SH treatment. Therefore, SH may serve as an effective therapy for CCEG by inhibiting bladder mucosal inflammation and proliferation.

Treatment of post-hematopoietic stem cell transplantation hemorrhagic cystitis with intravesicular sodium hyaluronate

Hemorrhagic cystitis (HC) is a well-known complication of HSCT. Its overall incidence has been reported to vary from 7-68%. The spectrum of clinical presentation varies from asymptomatic microhematuria to life-threatening bleeding. Sodium hyaluronate is a glycosaminoglycan present on the bladder mucosa, which serves as an important protective substance against uroepithelial damage. Preparations of this component have been shown to be effective in the treatment of interstitial cystitis. We report our experience in the treatment of post-transplant HC with intravesical instillation of sodium hyaluronate. Five out of the seven patients included in this study achieved complete response, while one patient had only partial response. Sodium hyaluronate administration was not associated with any local or systemic adverse effects. We consider that the results of our study are promising and the efficacy of sodium hyaluronate in the treatment of post-transplant HC should be tested in larger cohorts of patients.

Intravesicular glucose modulates magnesium2+ transport in liver plasma membrane from streptozotocin-treated rats

Plasma membrane vesicles purified from livers of 4-week-old streptozotocin-injected diabetic rats present an increased basal and cation-stimulated magnesium (Mg)2+ transport as compared with vesicles purified from age-matched nondiabetic animals. Furthermore, diabetic basolateral membranes are unable to accumulate extravesicular Mg2+ in exchange for intravesicular sodium (Na)+. Loading diabetic vesicles with varying concentrations of d-glucose, in addition to Mg2+, renormalizes basal and Na+- or calcium (Ca)2+-induced Mg2+ extrusion in a dose-dependent manner, but does not restore Na+/Mg2+ exchanger reversibility. A similar effect on Mg2+ extrusion is observed when d-glucose is replaced with 2-deoxy-glucose, amylopectin, or glycogen. The loading with 3-methyl-o-glucose or l-glucose, instead, affects basal and Na+-dependent Mg2+ extrusion, but not Ca2+-dependent Mg2+ fluxes. In contrast, loading the vesicles with hexoses other than glucose or varying extravesicular glucose concentration from 5 to 20 mmol/L does not modify basal or cation-stimulated Mg2+ fluxes. Taken together, these data indicate that basal and cation-stimulated Mg2+ transport across the hepatocyte plasma membrane is altered under diabetic conditions as a result of a decrease in intravesicular (intracellular) glucose.

Stimulus-secretion coupling in neurohypophysial nerve endings: a role for intravesicular sodium?

It is generally accepted that Ca is essentially involved in regulated secretion, but the role of this cation, as well as others such as Na, is not well understood. An illustrative example occurs in neurohypophysial secretion, where an experimentally induced increase in the cytosolic concentration of Na+ can induce continuous neuropeptide release. In contrast, an increase in cytosolic Ca2+ will have only a transient stimulatory effect. The secretion-promoting targets for Ca2+ are not known; they may be cytosolic, as is usually assumed, but they may also be intravesicular, especially in view of evidence that Ca-rich secretory vesicles are preferentially secreted. In the present work, we have investigated the movements of these cations into and out of secretory vesicles during stimulus-secretion coupling. Isolated rat neurohypophysial nerve endings were stimulated by potassium (55 mM) depolarization, and at 6 min (peak secretion) and 20 min after the onset of stimulation, the elemental content of individual secretory vesicles was measured by quantitative x-ray microanalysis. A depolarization-induced transient increase in intravesicular Na+ concentration was found to coincide with the onset of secretion. Moreover, only a predicted small fraction of peripheral vesicles-presumably the docked ones-were Na+-loaded. The low sulfur concentration of Na+-rich vesicles most likely resulted from vesicle swelling. The results suggest that high intravesicular Na+ concentrations in docked vesicles, occurring by Na+/Ca2+ exchange or by transient fusion pore opening, is a proximal event in exocytosis.

Sodium-calcium exchange in transverse tubules isolated from frog skeletal muscle

Transverse tubule vesicles isolated from frog skeletal muscle display sodium-calcium exchange activity, which was characterized measuring 45Ca influx in vesicles incubated with sodium. The initial rates of exchange varied as a function of the membrane diffusion potentials imposed across the membrane vesicles, increasing with positive intravesicular potentials according to an electrogenic exchange with a stoichiometry greater than 2 sodium ions per calcium ion transported. The exchange activity was a saturable function of extravesicular free calcium, with an apparent K 0.5 value of 3 μM and maximal rates of exchange ranging from 3 to 5 nmol/mg protein per 5 s. The exchange rate increased when intravesicular sodium concentration was increased; saturation was approached when vesicles were incubated with concentrations of 160 mM sodium. The isolated transverse tubule vesicles, which are sealed with the cytoplasmic side out, had a luminal content of 112±39 nmol calcium per mg protein. In the absence of sodium, the exchanger carried out electroneutral calcium-calcium exchange, which was stimulated by increasing potassium concentrations in the intravesicular side. Calcium-calcium exchange showed an extravesicular calcium dependence similar to the calcium dependence of the sodium-calcium exchange, with an apparent K 0.5 of 6 μM. Sodium-calcium and calcium-calcium exchange were both inhibited by amiloride. The sodium-calcium exchange system operated both in the forward and in the reverse mode; sodium, as well as calcium, induced calcium efflux from 45Ca-loaded vesicles. This system may play an important role in decreasing the intracellular calcium concentration in skeletal muscle following electrical stimulation.

The sodium gradient induces conformational changes in the renal phosphate carrier.

Phosphate transport across brush border membranes from kidney cortex is very sensitive to inhibition by phenylglyoxal, an arginine modifier. Sodium-dependent phosphate influx into brush border membrane vesicles was inhibited by 60%. In contrast, phenylglyoxal had no effect on passive influx or on sodium-dependent efflux of phosphate. Preincubation of the vesicles with sodium prior to the addition of phenylglyoxal demonstrated a strong protective effect of intravesicular sodium (73% protection). Phosphate also protected the transporter from inhibition, but from the extravesicular side only (63%). Substitution of phosphate by sulfate offered no protection at all, indicating the specificity of protection. Addition of both substrates (sodium and phosphate) offered an additional protection from the extravesicular side compared to that offered by phosphate alone (92 versus 55%). There was no additional protection when both substrates were added to the intravesicular side. Phosphate influx measured in the presence of sodium but in the absence of a sodium gradient was totally unaffected by phenylglyoxal modification. There was no inhibition on phosphate influx measured in equilibrium exchange conditions. We propose a model for the phosphate carrier in which the sodium gradient induces a conformational change and an arginine residue is essential for the coupled flux of sodium and phosphate.

Mechanisms of endotoxin-induced impairment in Na+-Ca2+ exchange in canine myocardium.

Effects of endotoxin administration on the Na+-Ca2+ exchange in canine cardiac sarcolemma were characterized. In addition, roles of phospholipase A2 and phosphorylation on the endotoxin-induced impairment in Na+-Ca2+ exchange were investigated. The results show that intravesicular sodium (Nai+)-dependent 45Ca2+ uptake was decreased by 39-66% (P less than 0.05) and extravesicular sodium (Nao+)-induced 45Ca2+ efflux was decreased by 36-52% (P less than 0.05) at 2 h following endotoxin administration. Ca2+o-induced 45Ca2+ efflux in the absence of Ko+ was not affected, but Ca2+o-induced 45Ca2+ efflux in the presence of Ko+ was significantly reduced by endotoxin administration. The stoichiometry of Na+-Ca2+ exchange was altered from 3 Na+ for 1 Ca2+ for the control to 2 Na+ for 1 Ca2+ for the endotoxin-treated dogs. The ATP-dependent 22Na+ uptake and Na+-Ca2+ exchange in inside-out vesicles remained unchanged after endotoxin injection. Digestion of control heart sarcolemmal vesicles with exogenous phospholipase A2 (0.02-0.06 unit/500 micrograms protein) inhibited Na+-Ca2+ exchange activity measured as Nai+-dependent 45Ca2+ uptake, and the inhibition was concentration dependent. Lysophosphatidylcholine addition to the control cardiac sarcolemma had no effect on Na+-Ca2+ exchange. The inhibition of Na+-Ca2+ exchange caused by phospholipase A2 digestion in the control heart sarcolemma was completely reversible by the addition of phosphatidylcholine (0.1 mM). The inhibition of Na+-Ca2+ exchange caused by the in vivo administration of endotoxin was completely reversible by the addition of phosphatidylcholine (0.1-0.15 mM).(ABSTRACT TRUNCATED AT 250 WORDS)

Sodium pump-catalyzed sodium-sodium exchange associated with ATP hydrolysis.

Inside-out red cell membrane vesicles have been used to study sodium interactions with the ATP-dependent sodium pump at sites accessible to both membrane surfaces. ATP-dependent 22Na+ influx (equivalent to efflux from cells) shows sigmoid dependence on extravesicular Na+ concentration. This is observed both in the absence of intravesicular cations and in the presence of intravesicular K or Rb ions. The kinetic behavior is similar to that observed earlier with intact cells, (Garay, R. P., and Garrahan, P. J. (1973) J. Physiol. (Lond.) 231, 297-325) and is consistent with a ratio of close to three Na ions transported per molecule of ATP hydrolyzed. With vesicles having relatively high intravesicular sodium concentration, (approximately 50 mM NaCl), the sodium pump effects an ATP-dependent sodium efflux coupled to sodium influx and to strophanthidin-sensitive ATP hydrolysis. The influx:efflux stoichiometry is approximately 1:1, and the influx:ATP hydrolysis ratio is close to 3. This ATP-dependent exchange has a higher affinity for vanadate than ATP plus ADP-dependent sodium exchange. It is concluded that this sodium-sodium exchange mode resembles sodium-potassium exchange whereby intravesicular sodium, i.e. sodium at the extracellular surface, at relatively high concentration, behaves like potassium.

Calcium movements promoted by vesicles in a highly enriched sarcolemma preparation from canine ventricle. Calcium-calcium countertransport.

Calcium uptake by vesicles in a highly enriched sarcolemma preparation from canine ventricle was found to be markedly stimulated by intravesicular calcium. Stimulation of calcium uptake appeared to be a saturable function of intravesicular calcium. Calcium efflux from the vesicles was stimulated by calcium in the reaction medium. Calcium uptake, supported by intravesicular calcium, and calcium efflux, stimulated by extravesicular calcium, were found to correspond on a one-to-one basis. Only small changes in net uptake or efflux were observed to occur in response to chemical gradients of calcium across the membrane. It was concluded, therefore, that under certain conditions, the major means for calcium movement across vesicles in the preparation is via a one-to-one exchange of calcium. Sodium was found to stimulate calcium uptake when present in the intravesicular space and to stimulate calcium efflux when present in the extravesicular space, but the effects of calcium plus sodium were not additive with respect to stimulating either calcium uptake or efflux. The effects of unlabeled calcium, strontium, barium, and magnesium on calcium uptake stimulated by intravesicular calcium and by intravesicular sodium were similar though not identical. The temperature dependence for calcium-stimulated and sodium-stimulated calcium movements was characterized by Q10 values of 1.27 and 2.06, respectively. Previous work has associated the sodium-calcium exchange reaction with the sarcolemma. It is argued that the present study, in turn, provides evidence that the calcium-calcium exchange reaction is also associated with the sarcolemma. In addition, the results of the study are consistent with the hypothesis that one membrane system can promote the exchange of either calcium for calcium or calcium for sodium.

Effect of intravesicular monovalent cations on the steady state of the phosphoenzyme of adenosine triphosphatase dependent on sodium and potassium ions in inside-out plasma-membrane vesicles.

Phosphorylation of the ATPase dependent on Na+ and K+ is promoted through the synergistic action of cations on both sides of the membrane. This phenomenon has been observed in plasma membrane vesicles isolated from sheep-kidney outer medulla which accept ATP from the outside surface (inside-out) and which are tight for sodium ions. In these inside-out vesicles phosphorylating capacity is low even in the presence of 100 mM extravesicular sodium chloride as is turnover of the enzyme. The level of the phosphoenzyme and the transient release of inorganic phosphate from the phosphoenzyme increases several-fold when sodium chloride is allowed to equilibrate over the membrane, 25 mM intravesicular NaCl is necessary to obtain the half-maximum level of the phosphoenzyme. This result shows that intravesicular (= extracellular) low affinity sites are involved in the phosphorylation. Intravesicular potassium ions modify the activating action of Na+ on the phosphorylation by increasing the steady state of the phosphoenzyme at low intravesicular sodium ion concentrations. This suggests that Na+ and K+ compete with each other for the intravesicular cation-binding site.

Mechanisms of Active Transport in Isolated Bacterial Membrane Vesicles: XIII. VALINOMYCIN-INDUCED RUBIDIUM TRANSPORT

Valinomycin-induced uptake of rubidium by membrane vesicles prepared from Escherichia coli, Staphylococcus aureus, and Micrococcus denitrificans is analogous in nearly all respects to the transport of sugars or amino acids, or both, by these membrane vesicles. In E. coli membrane vesicles, concentrative rubidium uptake is stimulated maximally by d -lactate and by the artificial electron donor ascorbate-phenazine methosulfate, to a lesser extent by l -lactate, dl -α-hydroxybutyrate, succinate, and reduced diphosphopyridine nucleotide, and not at all by ATP, phosphoenolpyruvate, or a number of other metabolites. There is no direct relationship between the ability of various electron donors to stimulate rubidium uptake (ascorbate-phenazine methosulfate >> d -lactate >> l -lactate g dl -α-hydroxybutyrate g succinate g reduced diphosphopyridine nucleotide) and their rates of oxidation by membrane vesicles (ascorbate-phenazine methosulfate >> reduced diphosphopyridine nucleotide g succinate g d -lactate g l -lactate g dl -α-hydroxybutyrate). In the presence of d -lactate and valinomycin, the initial rate of rubidium uptake versus the rate of d -lactate oxidation yields a ratio of nearly 2:1. Initial rates of d -lactate-dependent rubidium uptake are saturable with respect to rubidium and valinomycin concentrations and exhibit the same temperature optimum at 50° as that observed for d -lactate oxidation. Steady state levels of rubidium accumulation vary with temperature and can be shifted readily from one steady state level to another by raising or lowering the temperature. Competitive uptake and displacement experiments indicate that rubidium and potassium are equivalent substrates for valinomycin-induced uptake. Rubidium uptake in the presence of valinomycin is markedly inhibited by anaerobiosis, by the electron transfer inhibitors oxamate, amytal, 2-heptyl-4-hydroxyquinoline-N-oxide and cyanide, and by p-chloromercuribenzenesulfonate, but not by arsenate or dicyclohexylcarbodiimide; inhibition by p-chloromercuribenzenesulfonate is reversed by dithiothreitol. Moreover, anaerobiosis, amytal, 2-heptyl-4-hydroxyquinoline-N-oxide, and cyanide produce rapid efflux of rubidium from the vesicles. Oxamate and p-chloromercuribenzenesulfonate, however, cause little or no efflux of rubidium accumulated in the presence of valinomycin, even though p-chloromercuribenzenesulfonate-treated vesicles catalyze exchange of intravesicular rubidium with external potassium at normal rates. These findings indicate that valinomycin does not simply catalyze the passive transfer of rubidium across the vesicle membrane. Valinomycin-induced active rubidium uptake is accompanied by the rapid efflux of intravesicular sodium against its concentration gradient. The vesicles are passively permeable to the lipophilic dibenzyldimethylammonium ion; however, this cation does not inhibit rubidium uptake or rubidium-induced sodium efflux and does not cause sodium efflux. Moreover, radioactive dibenzyldimethylammonium is not accumulated by membrane vesicles under conditions in which rubidium is actively transported. Valinomycin, in the presence of potassium, has no significant effect on the transient acidification of the medium observed upon addition of d -lactate to the vesicles. In addition, vesicles treated with Tween 40 such that they are rendered devoid of a diffusion barrier exhibit pH changes similar to those of untreated vesicles. These findings indicate that active rubidium uptake is an electrogenic process and that proton or potential gradients are not the primary driving force for respiration-linked active transport in isolated bacterial membrane vesicles.