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Biomedical subjects

M Wakui

Publications and source records attributed to M Wakui.

At least 55 records · Page 3Linked to original sources
PubMed1996

Role of extracellular Ca2+ in acetylcholine-induced repetitive Ca2+ release in submandibular gland acinar cells of the rat.

Acetylcholine (ACh) caused repetitive transient Cl- currents activated by intracellular Ca2+ in single rat submandibular grand acinar cells. As the concentration of ACh increased the amplitude and the frequency of the transient Cl- currents increased. These responses occurred also in the absence of extracellular Ca2+ but disappeared after several minutes. Repetitive transient Cl- currents were restored by readmission of Ca2+ to the extracellular solution. The higher the concentration of extracellular Ca2+ readmitted, the larger the amplitude of the transient Cl- currents. Ca2+ entry through a store-coupled pathway was detected by application of Ca2+ to the extracellular solution during a brief cessation of stimulation with ACh. In these experiments too, the higher the concentration of Ca2+, the larger the transient Cl- currents activated by Ca2+ released from the stores. The time course of decrease in total charge movements of repetitive transient responses to ACh with removal of extracellular Ca2+ depended on a decrease in charge movements of each transient event rather than a decrease in frequency of the repetitive events. The decrease of charge movements of each transient event was due to a decrease in its amplitude rather than its duration. The results suggest that in this cell type and amplitude-modulated mechanism is involved in repetitive Ca2+ release and that Ca2+ entry is essential to maintain the repetitive release of Ca2+. The results further suggest that the magnitude of Ca2+ entry determines the number of unitary stores filled with Ca2+ which can synchronously respond to ACh.

Acetylcholine↗
PubMed1996

Excitatory and inhibitory actions of norepinephrine on the Ba2+ current through L-type Ca2+ channels of smooth muscle cells of guinea-pig vas deferens.

The effect of norepinephrine (NE) was examined on the whole-cell Ba2+ current through L-type Ca2+ channels of freshly isolated smooth muscle cells of guinea-pig vas deferens. The magnitude of maximum Ba2+ current [1Ba(max)] varied in different cells, although the capacitance of the cell membrane was similar (approximately 50 pF). Application of dbcAMP augmented 1Ba(max) by 37%, which was canceled by Rp-cAMPs, while PMA decreased the current by 32%, which was canceled by staurosporine. NE increased 1Ba(max) of the cells which originally showed relatively small 1Ba(max), and decreased the current of the cells which showed larger 1Ba(max). In the presence of phentolamine, NE increased 1Ba(max), and this effect was remarkable in cells showed smaller 1Ba(max). In the presence of propranolol, NE decreased 1Ba(max). The excitatory beta-adrenoceptor activation was canceled by Rp-cAMPs, and the inhibitory alpha-adrenoceptor effect was canceled by staurosporine. It is suggested that NE shows dual (excitatory and inhibitory) actions on the L-type Ca2+ channels of smooth muscle of guinea-pig vas deferens. The excitatory beta-adrenoceptor action mediated through cAMP/PKA is predominant in cells with lower density of the Ca2+ channels, while inhibitory alpha-adrenoceptor action mediated through PKC is predominant in cells with higher channel density.

Adrenergic Agonists↗
PubMed1996

Octanoate increases cytosolic Ca2+ concentration and membrane conductance in ovine pancreatic acinar cells.

In order to investigate the cellular mechanisms involved in amylase release in response to stimulation with short-chain fatty acids, changes in intracellular calcium concentration ([Ca2+]i), membrane current and amylase release were measured in pancreatic acinar cells of sheep. Both octanoate and acetylcholine raised [Ca2+]i in acinar cells in a concentration-dependent manner. The rise in [Ca2+]i in response to the stimulation with octanoate (10 mmol.l-1) was reduced in a medium without CaCl2, but was markedly enhanced by reintroduction of CaCl2 into the medium up to 2.56 mmol.l-1. Perfusion of the cells with a medium containing octanoate (5 mmol.l-1) or acetylcholine (0.5 mumol.l-1) immediately raised inward current across the cell membrane at a holding-membrane potential of -30 mV. The inward current became greater as the holding potential became more negative. The equilibrium potential was 1.8 mV and 3.9 mV for octanoate and acetylcholine, respectively, being consistent with that for Cl-. Although intracellular application of octanoate through a patch-clamp pipette also raised inward current after several minutes in some cells (4 out of 12), this possibility was significantly smaller than that for extracellular application. In other cells, even though the intracellular application of octanoate did not cause an increase in current, it always caused responses immediately after introduction of the fatty acid into the medium. Stimulation with fatty acid as well as acetylcholine raised amylase release in a concentration-dependent manner in cells dispersed from tissue segments with crude collagenase and trypsin inhibitor. Without trypsin inhibitor, crude collagenase significantly and selectively reduced the octanoate (10 mmol.l-1)-induced amylase release. Dispersion with crude collagenase and trypsin significantly reduced both responses induced by octanoate and acetylcholine (5.5 mumol.l-1). We conclude that fatty acids and acetylcholine increase [Ca2+]i, which consequently evokes a rise in transmembrane ion (Cl-) conductance and amylase release, and that trypsin-sensitive protein(s) in the cell membrane are involved in secretory processes activated by stimulation with fatty acids in ovine pancreatic acinar cells.

Acetylcholine↗
PubMed1996

Circulating endogenous thrombopoietin, interleukin-3, interleukin-6 and interleukin-11 levels in patients undergoing allogeneic bone marrow transplantation.

To elucidate the physiologic role of thrombopoietin (TPO) for hematologic reconstitution following allogeneic bone marrow transplantation (BMT), serum TPO levels as well as interleukin-3 (IL-3), IL-6 and IL-11 were serially measured in 55 samples from 3 patients who underwent allogeneic BMT using an enzyme-linked immunosorbent assay (ELISA). The TPO level was higher in the serum taken during marrow aplasia than in the pretransplant serum. The serum TPO levels and platelet counts showed a strong inverse relationship in all patients examined. We also sequentially measured endogenous serum TPO levels before and within 36 h after platelet transfusions. Endogenous serum TPO levels were inversely correlated with platelet mass following platelet transfusions. Serum levels of IL-3 had no apparent correlation with platelet counts and serum levels of IL-11 remained below the detection levels (31.3 pg/ml) in all samples. Serum levels of IL-6 were high during myeloaplasia and more upregulated in the febrile period. These findings support the view that TPO is the central regulator for megakaryopoiesis in vivo and the rationale for its clinical use after allogeneic BMT.

Adult↗
PubMed1996

Depletion of ryanodine-sensitive Ca2+ store activates Ca2+ entry in rat submandibular gland acinar cells.

The existence of ryanodine-sensitive Ca2+ stores and their role in the Ca2+ entry mechanism were examined in the rat submandibular gland acinar cells, using the microfluorimetry of intracellular Ca2+ concentration ([Ca2+]i). In the presence of thapsigargin, a Ca(2+)-ATPase inhibitor of inositol (1, 4, 5) triphosphate (InsP3)-sensitive Ca2+ stores, caffeine caused an increase in [Ca2+]i, which was inhibited by treatment with ryanodine (a ligand to the Ca(2+)-induced Ca2+ release channels). In the cells treated with ryanodine, 1 mM Ca2+ addition to a Ca(2+)-free solution caused a marked increase in [Ca2+]i, which was eliminated by application of Ni2+ or SK & F 96365, suggesting a Ca2+ entry triggered by ryanodine. The maximal change in the net increase in [Ca2+]i caused by the ryanodine-coupled Ca2+ entry, was 104.0 +/- 16.0 nM, which intense was caused by 10 microM ryanodine. Emptying the InsP3-sensitive stores by treatment with thapsigargin also caused Ca2+ entry, which maximally changed [Ca2+]i by 349.6 +/- 15.1 nM. Ten mumol/liter ryanodine was confirmed to cause a release of 45Ca2+ from the parotidic microsomal fraction enriched in endopalsmic reticulum. We propose that ryanodine-sensitive Ca2+ stores are present in rat submandibular gland acinar cells. We further propose that release of Ca2+ from the ryanodine-sensitive stores, which means eventually depletion of the ryanodine-sensitive Ca2+ stores, can activate the Ca2+ entry. The ability for Ca2+ entry coupled with the ryanodine-sensitive Ca2+ stores seems to be about 30% of the ability for Ca2+ entry coupled with the thapsigargin-sensitive Ca2+ stores.

Animals↗
PubMed1996

Durable molecular remission in a patient with chronic myelogenous leukemia and host-derived hematopoiesis after allogeneic bone marrow transplantation.

A 44-year-old woman with Ph-positive CML was treated with TBI, splenic irradiation, Ara-C, and CY. She then received unmanipulated marrow cells from her HLA-identical brother. GVHD prophylaxis was FK506 and MTX. WBC counts reached 1000/microliter on day 28 when all metaphases of marrow cells showed 46XY. However, on day 42, 46XX was detected in two of 20 metaphases, and the percentage of cells with female karyotype subsequently increased. On day 519, all metaphases showed female karyotype. BCR-ABL mRNA and Philadelphia chromosome were never detected throughout her post-transplant course. Fluorescence in situ hybridization (FISH) revealed complete recovery of host-derived hematopoiesis in the bone marrow, however, mixed T cell chimerism in the peripheral blood. This suggests that the persistence of donor-derived T cells may prevent disease recurrence through graft-versus-leukemia effect. The patient remains in a molecular complete remission with host-derived hematopoiesis 749 days post-transplant.

Adult↗
PubMed1995

Ca2+ entry through the store-mediated pathway directly activates only the K+ current but the subsequent Ca2+ release from the store activates both K+ and Cl- currents in submandibular gland acinar cells of the rat.

The store-mediated Ca2+ entry was detected in single and cluster of rat submandibular acinar cells by measuring the Ca2+ activated ionic membrane currents. In the cells where intracellular Ca2+ was partly depleted by stimulation with submaximal concentration of acetylcholine (ACh) under a Ca2(+)-free extracellular condition, an employment of external Ca2+ in the absence of ACh caused a sustained increase of the K+ current without affecting the Cl- current. A renewed ACh challenge without external Ca2+ caused repetitive spikes of both K+ and Cl- currents due to the Ca2+ release. SK & F 96365 inhibited the generation of the sustained K+ current and refilling of the Ca2+ store following the Ca2+ readmission. It is suggested that the Ca2+ enters the cell through the store-mediated pathway new the K+ channels and is taken up by the store. Thus, only Ca2+ released from the store can activate both the K+ and Cl- currents.

Acetylcholine↗
PubMed1995

Sr2+ can pass through Ca2+ entry pathway activated by Ca2+ depletion, but can be hardly taken up by the Ca2+ stores in the rat salivary acinar cells.

When Sr2+ was introduced to the external solution after the depletion of Ca2+ from stores of submandibular acinar cells by ACh stimulation, Sr2+ entered cytoplasm of the cell, like the case of Ca2+. SK&F 96365, a Ca2+ channel blocker, or Ni2+ blocked this divalent cation entry. Sr2+ entering the cell continued to increase to a steady level, after the cessation of stimulation, when Sr2+ was present in the external solution, unlike the case of Ca2+. Ca2+ entered cells which had been stimulated with ACh in Sr(2+)-containing external solution. In the cells to which Sr2+ has been applied after the store depletion with ACh, Sr2+ cannot be released by the renewed ACh stimulation, unlike the case of Ca2+. 89Sr2+ uptake by the parotidic microsomal fraction 100 min after addition of ATP was 15.08 +/- 0.70 nmol/mg protein, whereas 45Ca2+ uptake was 144.19 +/- 16.93 nmol/mg protein. It was concluded that in the salivary acinar cells Sr2+ can be a substituent for Ca2+ in the mechanism of entry from the extracellular fluid but cannot be in the mechanism of uptake into the stores.

Animals↗
PubMed1995

Stimulated Ca2+ entry activates Cl- currents after releasing Ca2+ from the intracellular store in submandibular gland cells of the rat.

In order to examine whether Ca2+ entry is directly involved in controlling exocrine secretion, the Ca(2+)-activated Cl- currents were recorded in single and clusters of rat submandibular gland cells using the whole-cell patch-clamp method. Extracellularly applied acetylcholine (ACh, 10 nM) as well as intracellularly applied GTP gamma S and InsP3 caused repetitive transients of the Cl- currents activated by intracellular Ca2+. These responses occurred also in the absence of external Ca2+, but disappeared after several minutes. Readmission of Ca2+ to the extracellular solution restored the repetitive current transients, while introduction of Sr2+ failed to restore the current signals in spite of the presence of Sr2+ entry detected by microfluorimetry. On the other hand, direct application of Sr2+ to the cell inside caused activation of the Cl- currents although less effectively than Ca2+. When Ca2+ was introduced to the extracellular solution during an interruption of ACh stimulation after the ACh-induced depletion of intracellular Ca2+ store, the Cl- current was not elicited. However, a subsequent challenge with ACh at the same concentration in the absence of extracellular Ca2+ caused repetitive transient Cl- currents. The results suggest that in this cell type the stimulated Ca2+ entry does not by itself activate the Cl- currents but activates them indirectly by triggering Ca2+ release from the intracellular Ca2+ store which may take up Ca2+ soon after the Ca2+ entry.

Acetylcholine↗
PubMed1994

Apically localized IP3 receptors control chloride current in airway gland acinar cells.

We examined the role of inositol 1,4,5-trisphosphate (IP3) receptors in acetylcholine (ACh)-induced chloride (Cl-) current in acinar cells of human and feline airway submucosal glands, using whole cell patch-clamp analysis. ACh (10 nM-1 microM) induced an initial Cl- current followed by a K+ current, and lower doses of ACh (1-10 nM) often induced oscillations of both currents, which were mimicked by the application of intracellular IP3. Neither isoproterenol (-10 microM) nor raising intracellular adenosine 3,5-cyclic monophosphate induced any current. Caffeine (20-50 mM) and intracellular ryanodine (1-100 microM) induced a K+ current alone without Cl- current. Monoclonal antibodies to the IP3 receptor abolished both ACh-induced K+ and Cl- currents. Immunohistochemical analysis revealed the localization of IP3 receptors on both the cytosol and some regions of the endoplasmic reticulum beneath the apical membrane of acinar cells. These results indicate that apically localized IP3 receptors control Cl- secretion from airway submucosal gland cells.

Acetylcholine↗
PubMed1993

[Sciatic nerve paralysis following intraarterial chemotherapy for bladder cancer: reports of two cases].

Bilateral sciatic nerve paralysis developed in two patients with invasive bladder cancer following intraarterial infusion of cisplatin (CDDP) and 4'-0-tetrahydropyranyladriamycin (THP) as preoperative adjuvant chemotherapy. Balloon catheters were selectively inserted into both internal iliac arteries, and CDDP 100 mg/m2 and THP 40 mg/m2 were administered under balloon occlusion. Pain of lower extremities developed soon after infusion and was gradually followed by paralysis. One patient recovered from paralysis partially after 4 months, but the other patient didn't recover. The use of balloon catheters resulted in an excessive concentration of chemotherapeutic agents with the adverse action on the sciatic nerves.

Aged↗
PubMed1992

Intracellular effects of aluminium on receptor-activated cytoplasmic Ca2+ signals in pancreatic acinar cells.

The hypothesis that intracellular aluminium may interfere with cytoplasmic Ca2+ signals evoked by the activation of receptors linked to inositol lipid hydrolysis has been tested. Single mouse pancreatic acinar cells were used, because there is much information in this system on the mechanism by which acetylcholine (ACh) evokes cytoplasmic Ca2+ oscillations (spiking) and these spikes can be monitored in internally perfused cells by measuring the Ca(2+)-dependent chloride current. ACh normally evokes repetitive Ca2+ spikes, but when aluminium (1 microM-1 mM) is present in the internal perfusion solution the responses are reduced or absent. When aluminium is acutely infused into the internal perfusion solution the ACh-evoked Ca2+ signals quickly disappear. Aluminium also inhibits Ca2+ signals evoked by the Ca2+ releasing agent caffeine. Preliminary results suggest that silicic acid may protect against the toxic effects of aluminium. Silicic acid and citrate, in the absence of added Al3+, have the effect of enhancing the ACh-evoked Ca2+ signals. This could be due to binding of traces of Al3+ in the solutions. We conclude that aluminium can disrupt receptor-activated cytosolic Ca2+ signals when present inside cells.

Aluminum↗
PubMed1991

Stimulatory and inhibitory actions of VIP and cyclic AMP on cytoplasmic Ca2+ signal generation in pancreatic acinar cells.

In pancreatic acinar cells the effects of vasoactive intestinal polypeptide (VIP) and dibutyryl cyclic AMP (dbcAMP) alone and during stimulation with acetylcholine (ACh) or internally applied inositol trisphosphate (InsP3) were investigated utilizing the patch-clamp whole-cell current recording configuration to assess changes in cytoplasmic Ca2+ concentration by measurement of Ca2+ dependent Cl- current. VIP (1 nM) and dbcAMP (0.5 mM) each evoked repetitive pulses of Ca(2+)-dependent Cl- current. A high VIP concentration (100 nM) acutely and reversibly inhibited the responses evoked by 1 nM VIP and also acutely inhibited ACh-evoked responses. DbcAMP (2 mM) also reversibly inhibited the ACh-evoked responses. Neither VIP nor dbcAMP were able to inhibit InsP3-evoked repetitive Ca2+ pulses. VIP in a low concentration can generate cytosolic Ca2+ oscillations via cyclic AMP, but high VIP concentrations inhibit both ACh and VIP-evoked Ca2+ signals and this effect is mediated by high intracellular cyclic AMP levels.

Acetylcholine↗
PubMed1991

Cytoplasmic Ca2+ signals evoked by activation of cholecystokinin receptors: Ca(2+)-dependent current recording in internally perfused pancreatic acinar cells.

The effects on the cytosolic Ca2+ concentration of activating cholecystokinin receptors on single mouse pancreatic acinar cells have been investigated using patch-clamp whole-cell recording of Ca(2+)-dependent Cl- current. We used the nonsulphated octapeptide of cholecystokinin (CCK8-NS) since the effects of even high concentrations were rapidly reversible which was not the case for the sulphated octapeptide. A submaximal concentration of CCK8-NS (10 nM) evoked a current response consisting of short-lasting (a few seconds) spikes, and some of these spikes were seen to trigger larger and longer (about half a minute) current pulses. At a higher concentration (100 nM) CCK8-NS evoked smooth and sustained responses. The effect of CCK8-NS was almost abolished when the internal perfusion solution contained a high concentration of the Ca2+ chelator EGTA (5 mM). The responses evoked by CCK8-NS were independent of the presence of Ca2+ in the external solution at least for the first 5 min of stimulation. Internal perfusion with GTP-gamma-S markedly potentiated the effect of CCK8-NS or at a higher concentration itself induced responses very similar to those normally evoked by CCK8-NS. Caffeine added to the external solution at a low concentration (0.2-1 mM) enhanced weak CCK8-NS responses, whereas high caffeine concentrations always inhibited the CCK8-NS-evoked responses. These inhibitory caffeine effects were quickly reversible. Forskolin evoked a similar inhibitory effect. Intracellular heparin (200 micrograms/ml) infusion markedly inhibited the response to CCK8-NS stimulation. We conclude that the primary effect of activating CCK receptors is to induce inositoltrisphosphate (IP3) production.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Incidence and mortality patterns of malignancy and factors affecting the risk of malignancy in dialysis patients.

A questionnaire study was performed among 23,209 dialysis patients in 589 institutions together with a retrospective study at Keio University Hospital to determine the risk of malignancy and factors affecting the risk ratio in dialysis patients. The incidence and mortality were 1.4-fold and 1.9-fold higher in dialysis patients than the expected rates in the general population. Incidence and mortality were 1.9-fold and 2.6-fold higher in males than in females. The risk ratios were remarkably high in university hospitals, followed by public hospitals. However, there was no significant difference between those in private hospitals and in the general population. The incidence was very high during the first 6 months of dialysis treatment and rather low in the 7th-10th year. The risk ratio of malignancy was higher in younger patients. Beyond the age of 60, the influence of age was greater than that of renal failure. Malignancies of the digestive organs were frequent and constituted 56% of all malignancies. Frequencies of malignancy in the liver, colon, rectum, bladder and kidney were higher than expected, whereas in the pancreas the frequency was lower than expected. Metastasis of malignancy was observed in 30% of the cases. Our study demonstrated a slight to moderate overall increase in the risk of malignancy and a widely differing risk ratio of malignancy by organ involved, sex, age, hospital group, epidemiological index and length of dialysis treatment in a large single racial population of maintenance dialysis patients.

Adult↗