大鼠心肌缺血再灌时血小板5—HT2A受体变化及腹蛇抗栓酶对心？…

本文观察了大鼠心肌缺血再灌注后血小板５－ＨＴ２Ａ受体，血浆５－ＨＴ，心肌ＣＰＫ的变化，及蛇毒抗栓酶对其影响，结果显示心肌缺血再灌后，血不板５－ＨＴ２Ａ受体Ｂｍａｘ和Ｋｄ及心肌ＣＰＫ明显减少，血浆５－ＨＴ明显升高，ＳＶＡＴＥ能逆转血小板５－ＨＴ２Ａ受本ＢｍａｘＫｄ以及心肌ＣＰＫ变化，但使血浆５－ＨＴ水平进一步升高，正常血小板在体外和２０μｍｏｌ／Ｌ５－ＨＴ温育后，５－ＨＴ２Ａ受体特异结合增加，在此基     

大鼠心肌缺血再灌时血小板5-HT_(2A)受体变化及腹蛇抗栓酶对心肌的保护作用

本文观察了大鼠心肌缺血再灌注后血小板５－ＨＴ２Ａ受体、血浆５－ＨＴ，心肌ＣＰＫ的变化，及蛇毒抗栓酶对其影响。结果显示心肌缺血再灌后，血小板５－ＨＴ２Ａ受体Ｂｍａｘ和Ｋｄ及心肌ＣＰＫ明显减少，血浆５－ＨＴ明显升高。ＳＶＡＴＥ能逆转血小板５－ＨＴ２Ａ受体Ｂｍａｘ、Ｋｄ以及心肌ＣＰＫ变化，但使血浆５－ＨＴ水平进一步升高。正常血小板在体外和２０μｍｏｌ／Ｌ５－ＨＴ温育后，５－ＨＴ２Ａ受体特异结合增加，在此基础上丙给同样剂量５－ＨＴ或与４０ｕｍｏｌ／Ｌ５－ＨＴ温育后５－ＨＴ２Ａ受体特异结合反而下降，ＳＶＡＴＥ同样能逆转受体特异结合的变化。据此，讨论了５－ＨＴ２Ａ受体变化与缺血再灌损伤关系及ＳＶＡＴＥ的保护机理。     

急性心肌梗塞患者血小板聚集性改变及药物的影响

急性心肌梗塞患者肾上腺素诱导血小板聚集性降低,与病情有一定关系,一般两周内恢复;5-羟色胺诱导聚集阳性率及不解聚率均明显高于正常对照组;每日口服100mg阿斯匹林明显抑制5-羟色胺及肾上腺素诱导聚集,但不能完全抑制尿激酶引起的血小板聚集增加;蝮蛇抗栓酶对5-羟色胺诱导聚集有明显抑制作用。     

大鼠垂体前叶5—羟色胺受体及黄体生成素免疫组织化学定位研究

目的;研究５－羟色胺受体在大鼠脑垂体前叶中的分布及５－羟色胺受体与黄体生成素的共存关系。方法：免疫组织化学ＡＢＣ法。结果：大鼠脑垂体前叶分布有５－羟色胺受体免疫反应阳性细胞,胞体较大,多边形或图形;黄体生成素阳性的内分泌细胞中含有５－羟色胺受体。结论：存在于垂体前叶的５－羟色胺能神经纤维,可能在垂体前叶的５－羟色胺受体介导下,直接参与垂体激素的合成与释放的调节。     

大鼠5－羟色胺能神经元相关营养因子的实验研究

本文从５，７－ＤＨＴ损伤的海马中制备了一种提取液，并测定了提取液对小脑内移植的胚胎５－ＨＴ神经细胞存活和生长的影响，结果显示１：２００烯释的提取液能显著增加神经细胞的存活率、神经纤维密度和５－羟色胺及５－羟哚乙酸的水平，同时移植区也明显增大，但１：１稀释的提取液对移植的中缝核神经细胞促进作用不明显。实验结果表明：①去５－ＨＴ神经的海马提取液含有某种海马释放的物质，属于损伤诱发的内源性物质。②该营养物质可直接或间接地促进５－ＨＴ神经元的生长和促进５－ＨＴ神经递质的合成与代谢。③高浓度提取液中可能存在某种抑制５－ＨＴ神经元生长的因子。     

5／6肾切除大鼠残肾血小板源生长因子—α表达及其意义的探讨

目的：研究慢性肾衰残余肾组织血小板源生长因子－α（ＰＤＧＦ－α）的表达状况及其机理和意义。方法：采用斑点杂交和形态计量等方法，对假手术对照大鼠、５／６肾切除大鼠、以及５／６肾切除术后给予维生素Ｅ治疗的大鼠肾组织ＰＤＧＦ－αｍＲＮＡ含量及其相关指标进行定量分析。结果：①５／６肾切除大鼠残存肾组织ＰＤＧＦ－αｍＲＮＡ含量显著增高；②５／６肾切除大鼠周围血单个核细胞内游离钙浓度显著增高，细胞内游离钙浓度与ＰＤＧＦ－αｍＲＮＡ含量成正相关；③５／６肾切除大鼠残肾组织有显著的固有细胞增殖、肾小球硬化和肾间质纤维化，肾组织羟脯氨酸含量显著增高，ＰＤＧＦ－αｍＲＮＡ含量与硬化肾小球比率、病变肾小管和肾间质体密度、肾组织羟脯氨酸含量成正相关；④给予维生素Ｅ治疗的大鼠，随着细胞内游离钙浓度和ＰＤＧＦ－αｍＲＮＡ含量降低，残肾硬化肾小球比率、病变肾小管和肾间质体密度、肾组织羟脯氨酸含量显著下降。结论：ＰＤＧＦ－α高表达可能是残存肾组织进行性纤维化的重要原因之一；维生素Ｅ治疗能降低ＰＤＧＦ－α表达，抑制残肾纤维化，减缓残肾毁损速度     

MAPK和Ca2+通路对介导弱氧修饰LDL增强HUVEC PAI-1活性

探讨弱氧化修饰低密度脂蛋白（mmLDL)对血管内皮细胞纤溶酶原激活物抑制剂（PAI－1）活性的影响及促分裂原活化蛋白激酶（MAPK）级联反应及第二信使Ca^2 在其中使用。用mmLDL作用于传代培养的人脐静脉内皮细胞（HUVEC），发色底物法检测PAI－1活性的变化，用激光共聚焦显微镜观察细胞内游离钙离子浓度的变化。结果显示，几种不同浓度的mmLDL(12.5-200mg/L)作用HUVEC 12h,PAI-1活性显著增加。PD98059（60μmol/L)能阻断mmLDL对PAI－活性的诱导反应。mmLDL(50mg/L)能显著诱导HUVEC胞内游离钙离子浓度增高。表明mmLDL作用HUVEC能诱导PAI－1活性明显增加，MAPK级联反应和胞内Ca^2 可能起到重要作用。     

尾加压素Ⅱ对大鼠肾小球系膜细胞内游离钙浓度影响

目的 探讨尾加压素Ⅱ（UmtensinⅡ，UⅡ）对肾小球系膜细胞（GMC）内游离钙浓度的影响及其作用机制。方法 以体外培养的SD乳鼠GMC为研究对象，用UⅡ刺激GMC，Fluo3／AM荧光标记细胞内游离钙离子，激光共聚焦显微技术动态测定GMC内游离钙浓度变化。结果 UⅡ激发GMC内[Ca^2＋]i升高作用分2个时相，即瞬时峰值升高时相和缓慢持久升高时相，对峰值升高呈剂量依赖方式，在10^-10mol／L～10^-7mol／L范围内引起峰值升高，且随着剂量增加，幅度增大。硝苯地平和无钙缓冲液对UⅡ激发GMC内[Ca^2＋]i瞬时峰值升高无作用，但可完全阻止缓慢持久升高时相出现。结论 UⅡ激发GMC内[Ca^2＋]i浓度瞬时峰值升高时相是由细胞内储存钙释放介导的，而缓慢持久升高时相是由细胞外钙流人增加引起的。     

慢性肾衰大鼠单个核细胞内游离钙浓度和白介素－1活性的变化

本文探讨了５／６肾切除术后慢性肾衰大鼠残肾纤维化的发生机理，发现术后１２０天，在残肾单个核炎性细胞浸润、残肾显著纤维化和肾功能损害的同时，残肾脂质过氧化物含量显著升高，抗氧化机制功能显著下降，钠钾ＡＴＰ酶活力显著下降，周围血单个核细胞内游离钙浓度显著升高，单个核细胞培养上清白介素－１活性增高。而摄入大量维生素Ｅ的大鼠，上述各指标有不同程度的改善，残肾纤维化显著减轻。提示残肾纤维化可能与单个核白细胞内游离钙浓度升高，进而产生白介素－１增多有关。     

虎杖甙对正常大鼠血管平滑肌细胞内游离钙浓度的影响

目的：观察虎杖甙（ＰＤ）对培养的大鼠血管平滑肌细胞（ＶＳＭＣ）内钙离子浓度的变化机理。方法：用Ｆｌｕｏ－３－ＡＭ标记培养的ＶＳＭＣ，在粘附式细胞仪上测定细胞内游离钙的变化。结果：实验结果表明，ＰＤ（００２～２０ｍｍｏｌ／Ｌ）可使大鼠ＶＳＭＣ内游离钙浓度升高，波形变宽，其引起的钙波形态与去甲肾上腺素（ＮＥ）及氯化钾所引起的高尖钙波不同，ＰＤ使ＶＳＭＣ产生一种剂量依赖性的、持续缓慢升高的钙波。ＰＤ引起的细胞内游离钙升高可被ＥＧＴＡ（２ｍｍｏｌ／Ｌ）及维拉帕米（５０μｍｏｌ／Ｌ）明显抑制。结论：以上结果提示ＰＤ既促进ＶＳＭＣ外钙离子进入细胞内，还能诱导细胞内钙离子释放；ＰＤ可能会提高正常ＶＳＭＣ的收缩性，增加正常血管的张力。     

Effects of pH on contraction and Ca2+ mobilization in vascular smooth muscles of the rabbit basilar artery

The present study was undertaken to investigate the effects of extracellular pH (pHe) and intracellular pH (pHi) on 5-hydroxytryptamine (5-HT)-induced contraction and Ca2+ mobilization in vascular smooth muscles. Strip preparations of the rabbit basilar artery without endothelium were loaded with 40 microM fura-2-AM and 2 microM BCECF-AM and mounted in an organ bath. The isometric tension was recorded by using a force displacement transducer. Administration of 5-HT caused dose-dependent contraction in the rabbit basilar arteries. Acidification of pHe from 7.40 to 6.90 reduced the 5-HT-induced contraction and [Ca2+]i transients. Alkalinization of pHe from 7.40 to 7.90, on the other hand, enhanced the contraction and elevation of [Ca2+]i. In the other series of experiments, pHi (7.12 in normal PSS) was selectively altered by adding either butyric acid or trimethylamine. Intracellular acidification (pHi = 6.89) and alkalinization (pHi = 7.35) without changes in pHe produced qualitatively similar effects to those caused by extracellular acidification and alkalinization, respectively. Ca-sensitivity, which is defined as Deltatension/Delta[Ca2+]i, was not affected by the alteration of pHe nor pHi. In the Ca2+-free solution, the addition of 5-HT produced transient increases in [Ca2+]i and isometric tension that were much smaller than those in the normal physiological salt solution. The 5-HT-induced responses of [Ca2+]i and tension in the Ca2+-free solution were not affected by acidification nor alkalinization. These results suggest that a 5-HT-induced contraction is significantly modulated by pH through changing the [Ca2+]i transients, and that the change of pHi plays, at least in part, a role in the alteration of 5-HT-induced contraction resulting from acidosis or alkalosis in the rabbit basilar artery.     

Electrophysiological recordings and calcium measurements in striatal large aspiny interneurons in response to combined O2/glucose deprivation.

Electrophysiological recordings and calcium measurements in striatal large aspiny interneurons in response to combined O2/glucose deprivation. The effects of combined O2/glucose deprivation were investigated on large aspiny (LA) interneurons recorded from a striatal slice preparation by means of simultaneous electrophysiological and optical recordings. LA interneurons were visually identified and impaled with sharp microelectrodes loaded with the calcium (Ca2+)-sensitive dye bis-fura-2. These cells showed the morphological, electrophysiological, and pharmacological features of large striatal cholinergic interneurons. O2/glucose deprivation induced a membrane hyperpolarization coupled to a concomitant increase in intracellular Ca2+ concentration ([Ca2+]i). Interestingly, this [Ca2+]i elevation was more pronounced in dendritic branches rather than in the somatic region. The O2/glucose-deprivation-induced membrane hyperpolarization reversed its polarity at the potassium (K+) equilibrium potential. Both membrane hyperpolarization and [Ca2+]i rise were unaffected by TTX or by a combination of ionotropic glutamate receptors antagonists, D-2-amino-5-phosphonovaleric acid and 6cyano-7-nitroquinoxaline-2, 3-dione. Sulfonylurea glibenclamide, a blocker of ATP-sensitive K+ channels, markedly reduced the O2/glucose-deprivation-induced membrane hyperpolarization but failed to prevent the rise in [Ca2+]i. Likewise, charybdotoxin, a large K+-channel (BK) inhibitor, abolished the membrane hyperpolarization but did not produce detectable changes of [Ca2+]i elevation. A combination of high-voltage-activated Ca2+ channel blockers significantly reduced both the membrane hyperpolarization and the rise in [Ca2+]i. In a set of experiments performed without dye in the recording electrode, either intracellular bis-(o-aminophenoxy)-N,N,N',N'-tetraacetic acid or external barium abolished the membrane hyperpolarization induced by O2/glucose deprivation. The hyperpolarizing effect on membrane potential was mimicked by oxotremorine, an M2-like muscarinic receptor agonist, and by baclofen, a GABAB receptor agonist. However, this membrane hyperpolarization was not coupled to an increase but rather to a decrease of the basal [Ca2+]i. Furthermore glibenclamide did not reduce the oxotremorine- and baclofen-induced membrane hyperpolarization. In conclusion, the present results suggest that in striatal LA cells, O2/glucose deprivation activates a membrane hyperpolarization that does not involve ligand-gated K+ conductances but is sensitive to barium, glibenclamide, and charybdotoxin. The increase in [Ca2+]i is partially due to influx through voltage-gated high-voltage-activated Ca2+ channels.     

Ca2+ uptake by the sarcoplasmic reticulum decreases the amplitude of depolarization-dependent [Ca2+]i transients in rat gastric myocytes

Gastric myocytes loaded with fura-2 were voltage-clamped at -60 mV. Depolarizations to 0 mV evoked nifedipine-sensitive (5 microM) inward currents and Ca2+ transients. Cyclopiazonic acid (5 microM) elevated steady-state [Ca2+]i and reduced Ca current (ICa), but when divalent cations were omitted from the extracellular solution, cyclopiazonic acid had no effect on either the amplitude or the current-voltage relationship of the nifedipine-sensitive current. This suggests that the reduction in ICa was caused by the rise in steady-state [Ca2+]i. The relationship between the total Ca2+ influx carried by the Ca2+ current (sigmaI(Ca).dt) and the amplitude of the Ca2+ transient (delta[Ca2+]i) was analysed for experiments using physiological Ca2+ solutions by calculating the ratio delta[Ca2+]i/sigmaI(Ca).dt. Cyclopiazonic acid (5 microM) and ryanodine (10 microM) both increased this ratio, indicating a decrease in the buffering power of the cell. Mimicking the increase in steady-state [Ca2+]i produced by these agents by changing the holding potential to -40 mV, however, did not affect delta[Ca2+]i/sigmaI(Ca).dt. It was concluded that up-take by a ryanodine-sensitive store normally limits Ca2+ distribution to the bulk cytoplasm following entry to the cell through dihydropyridine-sensitive channels.     

Contribution of Na+/Ca2+ exchanger to glucose-induced [Ca2+]i increase in rat pancreatic islets

The present study was carried out to elucidate the role of the reverse mode of the Na+/Ca2+ exchanger in an increase in intracellular Ca2+ concentration ([Ca2+]i) induced by a stimulatory concentration of glucose in rat pancreatic islets. The effects of KB-R7943, a selective inhibitor of reverse Na+/Ca2+ exchanger, on Na+o removal-induced [Ca2+]i changes were examined by a microfluorimetric method using fura-2 in perifused preparations of isolated rat pancreatic islets. Na+o removal induced a rapid increase in [Ca2+]i under 100 or 5 mM K+ conditions, respectively. The increases in [Ca2+]i induced by Na+o removal were inhibited by KB-R7943. The net amount of the [Ca2+]i increases during Na+o removal (Delta[Ca2+]i), obtained by subtracting the KB-R7943-independent Delta[Ca2+]i in the presence of KB-R7943 from Delta[Ca2+]i in the absence of KB-R7943, was significantly increased when extracellular K+ was raised. Increasing the external glucose concentration from 3 to 20 mM caused a biphasic increase in [Ca2+]i, which exhibited a transient increase (first phase) followed by a sustained increase (second phase) in [Ca2+]i. KB-R7943 (10 microM) partially inhibited the second phase of the [Ca2+]i increase rather than the first phase. These results suggest that the increase in [Ca2+]i induced by Na+o removal may be enhanced when plasma membrane is depolarized, and consequently, Ca2+ influx through the reverse Na+/Ca2+ exchanger may partially contribute to the glucose-induced [Ca2+]i dynamics in rat pancreatic islet cells.     

Effects of magnesium on prostacyclin synthesis and intracellular free calcium concentration in vascular cells.

This study investigated the effects of extracellular magnesium concentration ([Mg2+]e; 0.3-3 mM) on intracellular free calcium concentration ([Ca2+]i) and prostacyclin (PGI2) production in cultured human umbilical vein endothelial cells (HUVEC) and vascular smooth muscle cells from rats (VSMC) under basal and agonist-stimulated conditions. We used histamine as agonist which increases [Ca2+]i and PGI2 production in HUVEC, norepinephrine in VSMC. [Mg2+]e dose-dependently increased basal and agonist-stimulated PGI2 production in both cells. [Mg2+]e dose-dependently reduced basal [Ca2+]i in VSMC, but did not influence in HUVEC. In both cells, increasing [Mg2+]e reduced agonist-stimulated [Ca2+]i responses. Furthermore, [Mg2+]e dose-dependently reduced agonist-stimulated [Ca2+]i in Ca(2+)-free buffer, indicating intracellular Ca2+ release. In VSMC, 10(-6) M diltiazem and 10(-7) M nifedipine, Ca2+ channel blockers, reduced agonist-stimulated [Ca2+]i as well as 3 mM Mg2+, but did not affect PGI2 production. [Mg2+]e amplified dose-dependently arachidonic acid-induced PGI2 production in both cells, suggesting the activation of cyclooxygenase and/or PGI2 synthetase. Our results suggest that [Mg2+]e influences intracellular Ca2+ mobilization of not only vascular smooth muscle cells but also endothelial cells by inhibiting both Ca2+ influx and intracellular Ca2+ release. [Mg2+]e enhances PGI2 production in both types of cells, although the mechanism is likely to be independent from Ca2+ mobilization.     

Postsynaptic target regulates functional responses induced by 5-HT3 serotonin receptors on axonal varicosities of NG108-15 hybrid neuroblastoma cells

Rat brain presynaptic 5-HT3 serotonin receptors, members of the ligand-gated ion channel superfamily, induce changes in nerve terminal [Ca2+]i in a manner distinct from that found for somatic 5-HT3 receptors. Here, we assessed the role of postsynaptic target in regulating the nature of presynaptic receptor-induced responses, using the hybrid neuroblastoma cell line NG108-15 as a model neuronal system that expresses 5-HT3 receptors. Using immunocytochemistry, 5-HT3 receptors were found to be present on the presynaptic-like varicosities of differentiated NG108-15 cells, indicating that these receptors possess an inherent ability to localize to potential presynaptic sites. In the absence of postsynaptic target, 5-HT3 receptors localized to the varicosities induce rapid but transient changes in [Ca2+]i that were initiated by voltage-gated Ca2+ channels, as assessed using Ca2+ channel blockers, these properties being typical of those found for somatic 5-HT3 receptors. In co-cultures containing rat myotubes, with which NG108-15 cells form functional cholinergic synapses, the 5-HT3 receptor-induced changes in [Ca2+]i in the axonal varicosities shifted over time (three to 10 days) to that found for brain nerve endings: sustained responses that were insensitive to blockade by antagonists of voltage-gated Ca2+ channels. The effect of co-culturing myotubes with the NG108-15 cells was mimicked by conditioned media from myotube cultures. These results indicate that regulatory molecules from the target postsynaptic cell dictate the functional responses elicited by presynaptic 5-HT3 receptors. Because the target-induced changes required several days before they were evident, we hypothesize that changes in protein expression, perhaps the consequence of altered gene regulation, underlie the changes in the responses to 5-HT3 receptor activation in the axonal varicosities of this neuronal cell line.     

Effects of hypoxia on membrane potential and intracellular calcium in rat neonatal carotid body type I cells.

1. We have studied the effects of hypoxia on membrane potential and [Ca2+]i in enzymically isolated type I cells of the neonatal rat carotid body (the principal respiratory O2 chemosensor). Isolated cells were maintained in short term culture (3-36 h) before use. [Ca2+]i was measured using the Ca(2+)-sensitive fluoroprobe indo-1. Indo-1 was loaded into cells using the esterified form indo-1 AM. Membrane potential was measured (and clamped) in single isolated type I cells using the perforated-patch (amphotericin B) whole-cell recording technique. 2. Graded reductions in PO2 from 160 Torr to 38, 19, 8, 5 and 0 Torr induced a graded rise of [Ca2+]i in both single and clumps of type I cells. 3. The rise of [Ca2+]i in response to anoxia was 98% inhibited by removal of external Ca2+ (+1 mM EGTA), indicating the probable involvement of Ca2+ influx from the external medium in mediating the anoxic [Ca2+]i response. 4. The L-type Ca2+ channel antagonist nicardipine (10 microM) inhibited the anoxic [Ca2+]i response by 67%, and the non-selective Ca2+ channel antagonist Ni2+ (2 mM) inhibited the response by 77%. 5. Under voltage recording conditions, anoxia induced a reversible membrane depolarization (or receptor potential) accompanied, in many cases, by trains of action potentials. These electrical events were coincident with a rapid rise of [Ca2+]i. When cells were voltage clamped close to their resting potential (-40 to -60 mV), the [Ca2+]i response to anoxia was greatly reduced and its onset was much slower.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evidence for Na+/Ca2+ exchange in the rectal gland of Squalus acanthias

Previously we have shown that stimulation of in vitro perfused rectal gland tubules (RGT) of the dog-fish Squalus acanthias by adenosine 3',5'-cyclic monophosphate (cAMP), (as a cocktail comprising 0.1 mmol/l dibutyryl-cAMP, 10 micromol/l forskolin and 0.1 mmol/l adenosine, hereafter termed STIM) leads to an increase in cytosolic Ca2+ ([Ca2+]i) and that this assists Cl- secretion by enhancing basolateral K+ conductance. In the present study we examined the mechanism of the cAMP-induced increase in [Ca2+]i. [Ca2+]i was measured using the fura-2 technique in isolated in vitro perfused RGT. As before, STIM enhanced [Ca2+]i. This elevation of [Ca2+]i was prevented completely when STIM was added in the presence of the Na+2Cl-K+ cotransport inhibitor furosemide (0.5 mmol/l). This suggests that the increase in [Ca2+]i induced by STIM is caused by a concomitant increase in cytosolic Na+ ([Na+]i) and not by the activation of second messenger cascades. Furosemide prevents this increase in [Na+]i and hence the elevation of [Ca2+]i. Moreover, the plateau phase of the [Ca2+]i transient produced by carbachol (CCH, 0.1 mmol/l) was augmented strongly when bath Na+ was reduced to 5 mmol/l. These data suggest that the level of [Ca2+]i is determined by Na(+)-dependent Ca2+ export, most likely via a Na+/Ca2+ exchanger. The increase in [Na+]i accompanying stimulation of Cl- secretion reduces the rate of Ca2+ export leading to an elevation of [Ca2+]i, as does a reduction in bath Na+ which augments the [Ca2+]i plateau produced by CCH.     

Characterization of platelet cytoplasmic Ca2+ mobilization in patients with congenital cyclo-oxygenase deficiency and with defective platelet aggregation to A23187

Agonist-induced platelet cytoplasmic Ca2+ concentrations ([Ca2+]i) in patients with congenital cyclo-oxygenase deficiency (A) and with impaired aggregation to A23187 (B) were measured with aequorin in the presence or absence of extracellular Ca2+. The influence of TMB-8 or ONO3708 on agonist-induced [Ca2+]i in those platelets was also investigated. In Patient 1, there was a single aequorin luminescence peak in response to arachidonate, which was a thromboxane A2(TXA2) independent Ca2+ influx. The luminescence peak due to the formation of TXA2 was not detectable. The A23187-induced [Ca2+] i was decreased in the presence of extracellular Ca2+, but was within normal limits in the absence of extracellular Ca2+. A thrombin or STA2-induced elevation of [Ca2+] i was always within normal limits under any conditions. These results suggest that cyclo-oxygenase activity (CO activity) contributes to the A23187-induced Ca2+ influx, but does not contribute to the Ca2+ release from intracellular stores, and that the thrombin or STA2-induced Ca2+ influx and release do not depend on the CO activity. In Patient 2, the time lag from the addition of A23187 to the aequorin luminescence peak was found both in the presence and absence of extracellular Ca2+, which was more obvious in the latter. This A23187-induced elevation of [Ca2+] i disappeared after treatment of the platelets with TMB-8 in the absence of extracellular Ca2+, which is rarely seen in normal platelets. The most striking finding was that the thrombin-induced rise in [Ca2+] i in the absence of extracellular Ca2+ was not detectable. These findings might be closely related to abnormal platelet function in this patient.