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M Hashii

Publications and source records attributed to M Hashii.

29 records · Page 2Linked to original sources
PubMed1993

Bradykinin-induced cytosolic Ca2+ oscillations and inositol tetrakisphosphate-induced Ca2+ influx in voltage-clamped ras-transformed NIH/3T3 fibroblasts.

Microspectrofluorometry (fura-2) was combined with the whole-cell patch-clamp technique to study bradykinin-activated calcium (Ca2+) influx in single control or v-Ki-ras-transformed NIH/3T3 (DT) fibroblasts. Application of bradykinin on DT cells, but not on control NIH/3T3 cells, evoked cytosolic Ca2+ oscillations in the presence of extracellular Ca2+, but not in the absence of external Ca2+. This effect of zero external Ca2+ concentration could be mimicked by holding at depolarized membrane potentials. Cytosolic Ca2+ oscillations observed at holding potentials of -20 to -80 mV were terminated by holding at -10 mV or more depolarized potentials. The frequency of Ca2+ oscillations increased with membrane hyperpolarization. Bradykinin significantly enhanced the hyperpolarization-induced increases in the intracellular free Ca2+ concentration ([Ca2+]i) upon membrane hyperpolarization only in DT cells but not in control cells. No [Ca2+]i increase upon hyperpolarization was observed in bradykinin-stimulated DT cells in the absence of external Ca2+, suggesting that bradykinin activates Ca2+ influx. [Ca2+]i increased upon application of inositol 1,3,4,5-tetrakisphosphate (Ins(1,3,4,5)P4) into control and DT cells in an extracellular Ca(2+)-dependent manner, indicating that NIH/3T3 fibroblasts have an Ins(1,3,4,5)P4-gated Ca2+ influx pathway. Ins-(1,3,4,5)P4, however, produced the sustained [Ca2+]i increase in DT cells, but not in control NIH/3T3 cells, suggesting that ras may lock the Ca2+ influx pathway at the activated state. Cytosolic Ca2+ oscillations, bradykinin-enhanced Ca2+ influx, and Ins(1,3,4,5)P4-induced Ca2+ influx were all similar in that activity was increased by membrane hyperpolarization. The results suggest that bradykinin-induced cytosolic Ca2+ oscillations in ras-transformed NIH/3T3 cells are maintained by bradykinin-activated continuous Ca2+ influx which may use Ins(1,3,4,5)P4 as an intracellular messenger.

3T3 Cells↗
PubMed1992

Ion selectivity of Ba2+ inward current oscillations in ras-transformed fibroblasts that elicit cytoplasmic Ca2+ oscillations by bradykinin.

Ion selectivity of divalent cations on Ba2+ inward current oscillations was examined by voltage-clamp recording in v-Ki-ras-transformed NIH/3T3 (DT) fibroblasts where repetitive transient increases in cytoplasmic Ca2+ concentration were evoked by bradykinin. Application of bradykinin onto DT cells in 50 mM Ba2+ solution initiated Ba2+ inward current oscillations. The inward currents were inhibited in equimolar Sr2+ or Ca2+ solutions. Ba2+ current oscillations were dependent upon extracellular Ba2+ concentration. The results suggest that inward current oscillations are highly selective to Ba2+.

3T3 Cells↗
PubMed1992

Ba2+ current oscillations modulated by cyclic AMP and phorbol esters in ras-transformed fibroblasts.

An oscillatory influx of divalent cations was measured as Ba2+ inward currents (Ba2+ current oscillations) by voltage-clamp recording in v-Ki-ras-transformed NIH/3T3 (DT) fibroblasts after activation with bradykinin or serum. Application of forskolin or dibutyryl cyclic AMP onto DT cells initiated Ba2+ current oscillations. Increasing intracellular cyclic AMP reduced the amplitude but increased the frequency of the Ba2+ current oscillations. Activation of protein kinase C by phorbol esters terminated Ba2+ current oscillations. No inhibition of Ba2+ current oscillations by phorbol esters was observed in down-regulated cells that had been pretreated with phorbol esters for 24 hrs. The results suggest that Ba2+ current oscillations are regulated by intracellular second messengers.

3T3 Cells↗
PubMed1991

Ba2+ current oscillation evoked by bradykinin in ras-transformed fibroblasts.

By voltage-clamp recording, we show a novel inward current which oscillates after activation with bradykinin or serum in v-Ki-ras-transformed NIH/3T3 cells. The current oscillation was infrequently observed in control NIH/3T3 fibroblasts. The same stimulation evokes Ca2+ oscillations in the ras-transformed cells but not in parental cells (Fu et al., FEBS Lett. 281, 263-266, 1991). The results suggest that the oscillatory currents are generated by influxes of divalent cations to maintain Ca2+ oscillations in ras-transformed NIH/3T3 cells.

Animals↗
PubMed1991

[Coupling of muscarinic acetylcholine receptors, m1/m3 and m2/m4, to phosphoinositide metabolism and Ca2+ channels in DNA-transfected NG108-15 cells].

The muscarinic acetylcholine receptor (mAChR) is an integral membrane protein that transduces stimulus to effectors through the activation of guanine nucleotide-binding (G) proteins. Four or more subtypes of mAChR were detected in various tissues, and their primary structures were elucidated by cloning and sequence analysis of complementary DNA. Functional differences between them existed when they were expressed in clonal culture cells. mAChRI (m1) and mAChRIII (m3) preferentially activated phosphoinositide (PI) hydrolysis and opened Ca(2+)-activated K+ channels followed by closure of the M (K+)-currents, while such current activities were rarely evoked by mAChRII (m2)- and mAChRIV (m4)-transformed cells. Although it has been reported that mAChRII and mAChRIV inhibited adenylate cyclase, there was little or no such inhibition by mAChRI and mAChRIII. It is known that heart and neuronal mAChR modulate voltage-sensitive Ca2+ currents, but which species of mAChR subtypes are involved has been poorly understood. Recently we identified that endogenous mAChRIV and exogenous mAChRII expressed in NG108-15 neuroblastoma-glioma hybrid cells, but not mAChRI and mAChRIII, efficiently depressed high-threshold Ca2+ currents in a pertussis toxin-sensitive manner.

Animals↗
PubMed1991

Phosphoinositides and synaptic function in NG108-15 neuroblastoma x glioma hybrid cells.

1. The second-messengers system of bradykinin (BK) receptors was examined in NG108-15 neuroblastoma x glioma hybrid cells. 2. An application of BK induced an immediate outward (K+) current and acetylcholine (ACh) release, which are generated through inositol 1,4,5-trisphosphate (InsP3)-dependent Ca2+ ions. 3. Application of phorbol dibutyrate (a protein kinase C activator) produced a voltage-dependent inward current and inhibited another K+ (M)-current. 4. A similar current response has been produced by ACh in NG108-15 cells transfected with rodent muscarinic ACh receptor I and III subtype genes. 5. These results suggest a dual and time-dependent role for these two intracellular messengers in the control of neuronal signalling by BK and ACh.

Acetylcholine↗
PubMed1990

Selective coupling of different muscarinic acetylcholine receptors to neuronal calcium currents in DNA-transfected cells.

Acetylcholine (ACh) can inhibit calcium currents (ICa) in nerve cells by activating muscarinic ACh receptors (mAChR). There are several different genetic subtypes of mAChR. It is not known which subtype(s) are responsible for ICa inhibition. To resolve this issue, we measured ICa inhibition by ACh with patch-clamp recording, by using Ba2+ as charge carrier, in clones of NG108-15 neuroblastoma x glioma hybrid cells transfected with DNA for mAChRI, II, III and IV. Control (non-transfected) cells showed a mean maximum inhibition of peak ICa of 12.8 +/- 1.8% (n = 36) at 1 mM ACh. No consistent increase in inhibition was detected in vector-transfected cells, or in cells transformed to express mAChRI or mAChRIII. In contrast, inhibition was significantly increased in clones transformed to express mAChRII or mAChRIV. Inhibition was not correlated with the number of muscarinic receptors as determined by 3H-quinuclidinyl benzilate binding. Inhibition in both control and transfected cells was prevented by pretreatment with pertussis toxin (PTx). Inhibition persisted in the presence of extracellular or intracellular dibutyryl cyclic AMP, and hence is not because of inhibition of adenylate cyclase. We conclude that the inhibition of neuronal ICa is mediated preferentially by mAChRII and mAChRIV, via a PTx-sensitive GTP-binding protein.

Acetylcholine↗
PubMed1989

[Spastic paraplegia in Sjögren's syndrome associated with mixed connective tissue disease (MCTD)--a case report].

A case of spastic paraplegia in Sjögren's syndrome associated with mixed connective tissue disease is reported. In this 49-year-old woman spastic gait and arthralgia developed at the age of 23 years and progressed chronically. On neurologic examination, supranuclear paresis of facial nerve was observed. Deep tendon reflexes were hyperactive in the jaw, upper and lower extremities. Serological tests showed that anti-nuclear, anti-RNP, and anti-SS-A antibodies were positive. Spinal fluid analysis showed that rate of de novo central nervous system (CNS) IgG synthesis was increased, and C3/C4 ratio was elevated. CT scans of the brain showed calcifications at bilateral basal ganglia, dentate nucleus and cerebellar vermis. An electroencephalogram revealed diffuse slowing, and 123I-IMP brain scans revealed decreased cerebral blood flow. MRI of brainstem and cervical cord were normal. These findings suggested that corticospinal tracts upper the brainstem were severely affected, and that there were multifocal latent lesions in the CNS. Mechanisms of the CNS involvement were supposed to be both autoimmune abnormality in the CNS, and vascular impairment.

Central Nervous System Diseases↗
PubMedDate not supplied

Cyclic ADP-ribose as a second messenger revisited from a new aspect of signal transduction from receptors to ADP-ribosyl cyclase.

Cyclic ADP-ribose (cADPR), an endogenous modulator of ryanodine receptor Ca(2+)-releasing channels, is found in various tissues. Cytosolic injection of cADPR induces an elevation of intracellular Ca(2+) concentrations or potentiates Ca(2+) increases. cADPR facilitates neurotransmitter or insulin release and modifies ionic currents. cADPR is synthesized by ADP-ribosyl cyclase and is metabolized by cADPR hydrolase. ADP-ribosyl cyclase activity is up-regulated by nitric oxide/cyclic GMP-dependent phosphorylation or receptor stimulation via G-proteins within membranes. These findings suggest that cADPR is a second messenger in cellular Ca(2+) signaling. However, many intriguing issues remain to be addressed before this identity is confirmed.

ADP-ribosyl Cyclase↗