日本薬理学雑誌
Online ISSN : 1347-8397
Print ISSN : 0015-5691
ISSN-L : 0015-5691
101 巻, 3 号
選択された号の論文の9件中1~9を表示しています
  • 単離平滑筋細胞の薬理
    百瀬 和享
    1993 年 101 巻 3 号 p. 101-110
    発行日: 1993年
    公開日: 2007/02/06
    ジャーナル フリー
    In studies on the intrinsic contraction mechanisms of smooth muscle, various factors such as cell-to-cell interaction, penetration of chemicals to the trigger regions, or extracellular spaces in the tissue may influence the results. The use of single smooth muscle cells in such investigations may help to eliminate these factors. Single smooth muscle cells can be isolated from guinea pig taenia coli by digesting the minced tissue with a combination of collagenase and soybean trypsin inhibitor. The cells are spindle shaped, 100-200 μm in length and 10μm in diameter. Three kinds of techniques for determination of contractile responses of single smooth muscle cells have been established: 1) fixation method, 2) perfusion method, and 3) capillary adhesion method. Using these techniques, the cells appeared to be contracted in a dose-dependent manner (graded response), while another mode of the contractile response, the “all-or-none response”, has also been proposed. Scanning and transmission electron micrographs of the single cells revealed several evaginations of various sizes and shapes on the surface and electron dense bodies at the neck of the evaginations. ED50 obtained with the single cells, prepared from taenia coli of guinea pigs with collagenase in the presence of trypsin inhibitor was similar to that obtained with the intact tissue. Digestion of the tissue with highly purified collagenase and papain yields a large number of single cells with higher sensitivity to agonists. Characteristics of cells isolated from ileal longitudinal muscle of guinea pig are similar to those of cells isolated from taenia coli. The magnitude of contraction and sensitivity to acetylcholine were different in each cell. Incubation of isolated tissues with various concentrations of agonists followed by measurement of cell length in the tissue showed that the heterogeneous responses of the cells were intrinsic characteristics of smooth muscle cells and not due to damage incurred during the isolation procedure. Since isolated smooth muscle cells possess contractility, these might preserve the characteristics of smooth muscle, so they can be used for smooth muscle research. It must be considered, however, that each cell in the smooth muscle tissue has different contractility.
  • 単離平滑筋細胞の薬理
    高柳 一成, 佐藤 光利, 小池 勝夫
    1993 年 101 巻 3 号 p. 111-122
    発行日: 1993年
    公開日: 2007/02/06
    ジャーナル フリー
    Smooth muscle tissues were contracted by excitation of each muscle cell. Single cells prepared from guinea pig taenia caecum and trachea were contracted by extracellular application of acetylcholine and/or carbachol, whose concentrations were the same as those in the tissues. The concentration-response curve was shifted in a parallel fashion by competitive antagonists. The pA2-values of the antagonists were in good agreement with those estimated using the intact tissue. The apparent dissociation constants of cholinergic drugs estimated from inhibition of the specific binding of [3H] QNB (quinuclidinyl benzilate) to the single cells by the cholinergic drugs were also in agreement with the values in other membrane preparations. Similar findings were obtained in the single cells, microsomal fractions and isolated tissues from the guinea pig tracheal smooth muscles. In rabbit aortic single cells, the existence of two pharmacologically distinct α1-adrenoceptor subtypes, α1A and α1B, in vascular smooth muscle cells was supported. Furthermore, the amount of prostaglandin F released from guinea pig tracheal single cells was increased through activation by α2-adrenoceptor agonists. The amount of prostaglandin F released by norepinephrine decreased with age, while the total amount of α2-adrenoceptors and the dissociation constants of the α2-adrenergic drugs from the receptor did not change. The relaxation induced by β-adrenoceptors did not alter with age. The total amount of β-adrenoceptor and the dissociation constants of β-adrenergic drugs from their receptor did not alter with age. An excellent relationship between the potency of isoprenaline and the maximum binding of [3H] dihydroalprenolol estimated in the single cells from 6- to 40-week-old guinea pigs was found, suggesting that the increase in the potency of isoprenaline is due to the increase in the maximum binding. The value in the single cells from 100-week-old guinea pigs deviated significantly from the regression line. This result suggests that the decrease in potency in the single cells from 100-week-old animals is due to a change in post β-receptor processes in responsiveness. The smooth muscle single cells are useful for the study of drug-receptor interactions. Furthermore, post-receptor processes in responsiveness were discussed.
  • 単離平滑筋細胞の薬理
    三田 充男, 大石 一彦, 橋本 孝雄, 内田 幸宏
    1993 年 101 巻 3 号 p. 123-131
    発行日: 1993年
    公開日: 2007/02/06
    ジャーナル フリー
    Most isolated smooth muscle cells from guinea pig taenia caecum responded repeatedly, showing an all-or-none response to acetylcholine (ACh). However, the average responses of all the cells were graded owing to the difference in the threshold concentration of ACh, like that of whole tissue. The sensitivity of the muscarinic receptor on individual cells was the same as that of whole tissue and ACh bound to the receptor concentration-dependently. The shortening of the cells in response to ACh depended upon the influx of extracellular Ca2+ through the Ca channel. 45Ca2+ influx stimulated by ACh was very sharp and highly correlated with the shortening of the cells. The shortening of α-toxin-permeabilized smooth muscle cells was induced by increasing free Ca2+. The concentration-response relationship to free Ca2+ had a very steep slope, and the shortening appeared to be an all-or-none response rather than a graded response. In conclusion, it is suggested that isolated smooth muscle cells show an all-or-none response as a result of a slight increase in the intracellular free Ca2+ level over the threshold concentration when early signalling coupled to ACh-receptor stimulation reaches the threshold to evoke Ca2+ influx and Ca2+ release.
  • 単離平滑筋細胞の薬理
    飯野 正光, 山澤 徳志子, 遠藤 實
    1993 年 101 巻 3 号 p. 133-142
    発行日: 1993年
    公開日: 2007/02/06
    ジャーナル フリー
    This paper briefly reviews our current effort to study the Ca2+ mobilization mechanism in enzymatically dispersed single smooth muscle cells. Each single cell obtained from guinea pig taenia caeci possesses two types of Ca2+ stores, one (Sα) with both Ca2+-induced and IP3-induced Ca2+ release mechanisms and the other (Sβ) with only IP3-induced Ca2+ release mechanism. After depletion of Sα either with ryanodine treatment or with caffeine pretreatment, carbachol failed to induce Ca2+ release, while intracellular application of IP3 did induce Ca2+ release. Our results suggest that the difference between the agonist and IP3-induced responses can be resolved by obligatory involvement of positive feedback control of IP3-induced Ca2+ release in the agonist-induced Ca2+ release. Furthermore, we were able to demonstrate that the dose-response relation in single cells shows an all-or-none feature, which seems at least partly due to the feedback control of Ca2+ release. We discuss the reasons why graded dose-response relation is obtained in bundles of smooth muscles, while the response of single cells is an all-or-none type.
  • 単離平滑筋細胞の薬理
    小原 一男, 薮 英世
    1993 年 101 巻 3 号 p. 143-151
    発行日: 1993年
    公開日: 2007/02/06
    ジャーナル フリー
    The voltage-dependent Ca2+ channels (VDC) in smooth muscle cell membranes are the major pathway by which Ca2+ enters the cell during contraction. It has been reported that VDC can be modulated by reversible channel protein phosphorylation and dephosphorylation reactions. In intestinal smooth muscle cell, muscarinic agents have been reported to increase the break-down of phosphatidylinositol 4, 5-bisphosphate, which indicates that inositol-1, 4, 5-trisphosphate and diacylglycerol (DG) can be generated. DG activates protein kinase C. Carbachol (CCh), phorbol 12, 13-dibutyrate and phosphatase inhibitors, okadaic acid and calyculin A increased the inward currents passing through the L-type VDCs. These effects were inhibited by protein kinase inhibitors, H-7 and staurosporine. The CCh effect was also inhibited by GDPβS. Therefore, it seems possible that DG, a product of phosphatidylinositol break-down might mediate muscarinic effects on L-type VDC, the last via stimulation of protein kinase C, and that L-type VDC activity might be modulated by protein kinase C-mediated phosphorylation and protein phosphatase type-1-mediated dephosphorylation of the channel or related protein(s) in guinea pig taenia coli smooth muscle cells.
  • 単離平滑筋細胞の薬理
    今泉 祐治, 村木 克彦, 辺見 智, 渡辺 稔
    1993 年 101 巻 3 号 p. 153-167
    発行日: 1993年
    公開日: 2007/02/06
    ジャーナル フリー
    The major functional roles of K channels in smooth muscle cells are as follows: (i) Keeping resting membrane potential (RMP). (ii) Induction of hyperpolarization (HP) in response to bioactive substances. (iii) Facilitation of action potential repolarization (APR). (iv) Induction of action potential afterhyperpolarization (AH). (v) Facilitation of slow wave repolarization. (vi) Inhibition of depolarization and/or action potential. Major background K channels responsible for RMP have not been identified yet, whereas it is been postulated that several K channels including Ca-dependent K channels and ATP-dependent K channels may co-contribute in part to RMP. Further activation of these channels by bioactive substances results in hyperpolarization and muscle relaxation. APR and AH in several types of smooth muscles are due to activation of mainly large conductance Ca-dependent K channels (BK) and additionally delayed rectifier K channels. Moreover, another type of delayed rectifier K channels and early inactivating K channels may also contribute to some of the functional roles shown above. Although activation of Ca-dependent Cl channels in response to agonists depolarizes the cell membrane in several types of smooth muscle cells, a single channel current has not been identified. Ca-dependent K and Cl currents can be regulated by intracellular Ca store sites, which may be exhausted after a large release induced by inositol 1, 4, 5-trisphosphate or caffeine. The Ca-pump activity in the store sites may also regulate indirectly but strongly the activity of the channels and consequently membrane excitability.
  • 山本 和典, 高瀬 英樹, 阿部 健一, 齋藤 雄二, 鈴木 章
    1993 年 101 巻 3 号 p. 169-175
    発行日: 1993年
    公開日: 2007/02/06
    ジャーナル フリー
    ベルベリン配合製剤の各種下痢モデルに対する作用ならびに各種刺激による摘出腸管平滑筋の収縮に対する作用を,クレオソート製剤及びロペラミドのそれと比較した.ベルベリン配合製剤は,クレオソート製剤及びロペラミドと同様に,ヒマシ油ならびに塩化バリウム誘発下痢を有意に抑制したが,ピロカルピンならびにセロトニン誘発下痢に対して有意な作用を示さなかった.また,ベルベリン配合製剤は,回腸ならびに結腸のアセチルコリン,バリウム及び経壁電気刺激による収縮反応を同濃度(10-6~10-4g/ml)で抑制した.一方,クレオソート製剤は,アセチルコリン及びバリウムによる収縮よりも経壁電気刺激による収縮反応を100倍強く抑制した.また,ロペラミドは,回腸収縮において経壁電気刺激>バリウム>アセチルコリンの順に刺激反応を抑制し,結腸に対する作用は回腸に対するそれよりも弱かった.以上の結果から,ベルベリン配合製剤は,クレオソート製剤及びロペラミドとは異なった作用機序によって,腸管運動を抑制することにより,止瀉作用を発揮することが推察された.
  • 松村 敏弘, 古市 浩康, 泉 順吉, 鎌塚 由弥子, 武井 峰男, 中田 直樹, 伊藤 茂, 須田 浩守, 木崎 久仁枝, 栗本 忠
    1993 年 101 巻 3 号 p. 177-186
    発行日: 1993年
    公開日: 2007/02/06
    ジャーナル フリー
    カルシウム拮抗薬NC-1100の作用について検討した.本薬剤の各種脳虚血およびアノキシアモデルに対する最小有効量はKCN誘発アノキシアでは8mg/kg(i.p.)および30mg/kg(p.o.),断頭虚血モデルでは16mg/kg(i.p.),常圧低酸素試験では16mg/kg(i.p.),減圧低酸素試験では32mg/kg(i.p.),スナネズミ一過性脳虚血モデルでは30mg/kg(i.p.)およびスライス切片を用いたin vitro虚血モデルでは10μMであった.さらに,断頭虚血モデルにおいてNC-1100は脳エネルギー代謝改善作用を示した.以上のことから,NC-1100は脳障害保護作用を有しており,その作用の一部には脳エネルギー代謝改善作用が関与していることが示唆された.
  • 増田 幹生, 武田 弘志, 渋谷 健
    1993 年 101 巻 3 号 p. 187-196
    発行日: 1993年
    公開日: 2007/02/06
    ジャーナル フリー
    ストレス適応の形成機構における中枢モノアミン作働性神経系の役割を考究する目的で,反復拘束ストレスに対する適応形成ならびに非形成時の脳,脊髄内ノルエピネフリン(NE),ドーパミン(DA)およびセロトニン(5-HT)作働性神経系の動態特性を神経化学的に検討した. ラットに1日1あるいは2時間の拘束ストレスを7日間反復負荷することにより,体重変化率,摂食量,摂水量および自発運動量の減少,疼痛閾値の増加などのストレス反応が消失し,ストレスに対する適応が形成された. 一方,1日4時間の7日間反復負荷条件下では,ストレス反応の発現は維持され,適応は形成されなかった. 反復拘束ストレスに対して適応を形成したラット(適応モデル)に共通して,大脳皮質前頭部,中脳-視床,線条体,視床下部,延髄-橋,小脳の各脳部位および頸髄,胸髄,腰髄の各脊髄部位で5-HT代謝回転の著明な増加が認められた.また,この適応モデルに共通して脊髄内NE代謝回転の増加が観察されたが,脳内NEおよび脳,脊髄内DA代謝回転の変化には共通性は認められなかった. 一方,反復拘束ストレスに対して適応を形成しないラット(非適応モデル)では,視床下部および腰髄での5-HT代謝回転の増加が観察されたが,他の脳,脊髄部位では何ら変化が生じなかった. さらに,この非適応モデルの大脳皮質前頭部,線条体および頸髄においてNE代謝回転の減少が認められた. しかし,DA代謝回転に関しては,脳および脊髄のいずれの部位においても変化が生じなかった. 以上の所見から,反復拘束ストレスに対する適応の形成には,5-HT代謝回転の増加に起因する脳,脊髄内5-HT作働性神経系の活性亢進およびNE代謝回転増加に伴う脊髄内NE作働性神経系の活性亢進が関与することが示唆される.
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