Calmidazolium-induced rises in cytosolic calcium concentrations in Madin Darby canine kidney cells

The effect of calmidazolium on Ca(2+) signaling in Madin Darby canine kidney (MDCK) cells was investigated using fura-2 as a Ca(2+) probe. Calmidazolium at 2-5 microM increased [Ca(2+)](i) concentration dependently. The [Ca(2+)](i) rise induced by 2-5 microM calmidazolium comprised an immediate rise and a slow decay. External Ca(2+) removal partly inhibited the Ca(2+) signals, suggesting that calmidazolium activated external Ca(2+) influx and internal Ca(2+) release. In Ca(2+)-free medium, pretreatment with 3 microM calmidazolium abolished the Ca(2+) release induced by 1 microM thapsigargin, an endoplasmic reticulum Ca(2+) pump inhibitor, and, vice versa, pretreatment with thapsigargin inhibited calmidazolium-induced Ca(2+) release. This indicates that thapsigargin-sensitive Ca(2+) store was the source of calmidazolium-induced Ca(2+) release. Calmidazolium (3 microM) induced Mn(2+) quench of fura-2 fluorescence at 360 nm excitation wavelength, which was suppressed by 0.1 mM La(3+). Addition of 3 mM Ca(2+) increased [Ca(2+)](i) after pretreatment with 3-5 microM calmidazolium in Ca(2+)-free medium. This implies that calmidazolium activated concentration-dependent capacitative Ca(2+) entry. Calmidazolium (3 microM) augmented the capacitative Ca(2+) entry induced by 1 microM thapsigargin or 0.1 mM ATP by 38%. Calmidazolium (3 microM)-induced Ca(2+) release was blocked by pretreatment with 40 microM aristolochic acid and 2 microM U73122 (2 microM) to inhibit phospholipase A(2) and phospholipase, respectively, but pretreatment with 0.1 mM propranolol to inhibit phospholipase D had no effect. This suggests that calmidazolium induced internal Ca(2+) release in a manner dependent on phospholipases C- and A(2)-coupled events.     

粉防己碱对培养大鼠心肌细胞胞内游离钙的影响(英文)

目的:研究粉防己碱对心肌的作用。方法:采用Fura-2和AR-CM-MIC阳离子测定系统测定培养大鼠单个心肌细胞胞内游离钙。结果:外钙1.3mmol·L~(-1)时,细胞静息钙为90±12nmol·L~(-1)。粉防己碱不影响静息钙,但可明显抑制CaCl_2,KCl,哇巴因引起的胞内钙增高;对于去甲肾上腺素引起的胞内钙增高,粉防己碱只有在外钙存在时,方对其有抑制作用。结论;粉防己碱抑制钙离子的跨膜运动,但在心肌细胞,它并非是选择性的钙通道阻滞剂。     

蝙蝠葛苏林碱对PC12细胞内游离钙浓度的影响

目的进一步探讨蝙蝠葛苏林碱（Dau）的抗脑缺血／缺氧损伤与其钙拮抗作用间的关系。方法：培养的PC12细胞用Fura－2／AM负载，用AR－CM－MIC阳离子测定系统观测Dau对单细胞内游离钙（[Ca(2+)]_i）升高的影响。结果：Dau（0．1～100μmol·L(－1)）可浓度依赖性抑制高钾和caffeine引起的[Ca(2+)］_i增加，对肌浆网钙泵抑制剂cy－clopiszonicacid引起的[Ca(2+)]_i升高也有抑制作用。结论：Dau不仅抑制电压依赖性钙通道开放引起的细胞外钙内流和caffeine引起的内钙释放．而且对钙泵也可能有影响，这可能是其抗脑缺血／缺氧损伤的重要机制。     

Rapid action of pesticides on cytosolic calcium concentrations in cultures of human umbilical vein endothelial cells

Persistent metabolites of pesticides such as p,p'-DDE, at environmentally relevant concentrations, have been shown to have a rapid effect on intracellular calcium [Ca2+]i concentrations in human granulosa-lutein cells. Since endocrine disrupting substances can be transferred from the maternal circulation to the fetus the present study examined whether the pesticides, kepone, o,p-DDE, p,p'-DDE and methoxychlor, could alter cytoplasmic calcium [Ca2+]cyt concentrations in human umbilical vein endothelial (HUVE) cells. Cultured HUVE cells were loaded with Fura-2 AM and changes in [Ca2+]cyt of single cells were studied using a dynamic digital Ca2+ imaging system. Kepone and methoxychlor consistently increased [Ca2+]cyt concentrations, similar to the effects of estradiol and progesterone. p,p'-DDE increased [Ca2+]cyt concentrations in 80% of experiments whereas o,p-DDE stimulated its increases in 42%. Estrone, estriol, pregnenolone and cortisol were not effective. These results demonstrate that pesticides can have a rapid effect on HUVE cells probably through a nongenomic mechanism of action.     

Effects of glibenclamide on cytosolic calcium concentrations and on contraction of the rabbit aorta.

1. Using fluorometry of fura-2 and rabbit aortic strips, we studied the effects of glibenclamide (GLB), a sulphonylurea anti-diabetic drug and an inhibitor of opening of K+ channels, on cytosolic calcium concentrations ([Ca2+]i) and on force development. 2. Both high K(+)-depolarization and noradrenaline (NA) increased [Ca2+]i and force, in a concentration-dependent manner, in the presence of extracellular Ca2+ (1.25 mM). However, force development in relation to [Ca2+]i ([Ca2+]i-force relationship) observed with NA was much greater than that observed with K(+)-depolarization. 3. Pretreatment with GLB (10(-6)-10(-4) M) for 10 min partially inhibited, in a concentration-dependent manner, both [Ca2+]i elevation and the force development induced by 118 mM K(+)-depolarization or NA 10(-5) M in the presence of extracellular Ca2+. The [Ca2+]i-force relationship induced by both 118 mM K+ physiological salt solutions and by NA 10(-5) M in the GLB-treated strips overlapped that obtained in the non-treated strips, thereby suggesting that GLB has no effect on the Ca2(+)-sensitivity of the intracellular contractile apparatus. Only high concentrations (10(-4) M) of GLB decreased [Ca2+]i and the force, when applied after the force induced by 118 mM K+ PSS or NA 10(-5) M reached the maximum level. 4. In the absence of extracellular Ca2+, NA induced a transient increase in [Ca2+]i and in the force and these increases were inhibited when the vascular strips were pretreated with GLB for 10 min. The [Ca2+]i-force relationship obtained in the GLB-treated strips overlapped that in the non-treated ones.(ABSTRACT TRUNCATED AT 250 WORDS)     

小檗胺对ROCC介导的血管平滑肌细胞内游离钙的影响

目的　研究小檗胺 (BA)对受体调控性Ca2 +通道介导的家兔胸主动脉血管平滑肌细胞内游离钙 ([Ca2 +]i)的影响。方法　家兔主动脉血管平滑肌以Fluo 3/AM负载 ,通过激光扫描共聚焦显微镜 (LSCM )测定 [Ca2 +]i。结果　在细胞外Ca2 +存在的条件下 ,BA 30 μmol·L-1不影响静息[Ca2 +]i;但对去甲肾上腺素 (NE) 30mmol·L-1、5 羟色胺 (5 HT) 1μmol·L-1诱导的 [Ca2 +]i 升高有明显的抑制作用。在无胞外钙时 ,对咖啡因 40mmol·L-1诱导的 [Ca2 +]i 升高没有作用。结论　BA对ROCC激活后的外钙内流有明显的抑制作用 ,对内钙释放没有影响。其作用与维拉帕米相似     

左旋千金藤定碱对培养牛主动脉血管平滑肌细胞胞内游离Ca~(2+)的影响

目的：研究左旋千金藤定碱（ｌ－ｓｔｅｐｈｏｌｉｄｉｎｅ，ＳＰＤ）对血管平滑肌的作用。方法：采用Ｆｕｒａ－２和ＡＲ－ＣＭ－ＭＩＣ阳离子测定系统测定培养牛主动脉血管平滑肌细胞内游离钙。结果：ＳＰＤ１～１００μｍｏｌ·Ｌ－１不影响静息［Ｃａ２＋］ｉ，但可剂量依赖地抑制高Ｋ＋引起的［Ｃａ２＋］ｉ增高，其ＩＣ５０为３９．６（９５％可信限２３．４～６７．１）μｍｏｌ·Ｌ－１，但其作用弱于尼群地平；ＳＰＤ１～１００μｍｏｌ·Ｌ－１对去甲肾上腺素、血管紧张素Ⅱ、５－ＨＴ、ＡＴＰ引起的［Ｃａ２＋］ｉ增高也有明显的抑制作用；高浓度ＳＰＤ对无外钙时去甲肾上腺素引起的［Ｃａ２＋］ｉ增高也有一定的抑制作用。结论：左旋千金藤定碱对培养血管平滑肌细胞电压依赖性钙通道和受体调控性钙通道均有抑制作用；其对电压依赖性钙通道的抑制作用弱于尼群地平。     

Regulation of cytosolic calcium in skeletal muscle cells of the mdx mouse under conditions of stress.

1. In Duchenne muscular dystrophy (DMD) dysregulation of cytosolic calcium appears to be involved in the degeneration of skeletal muscle fibres. Therefore, we have studied the regulation of the free cytosolic calcium concentration ([Ca2+]c) under specific stress conditions in cultured myotubes isolated from the hind limbs of wild-type (C57BL10) and dystrophin-deficient mutant mdx mice. [Ca2+]c in the myotubes was estimated by the use of the Ca(2+)-sensitive fluorescent dye, fura-2. 2. Resting [Ca2+]c was similar in mdx and normal myotubes (35 +/- 9 nM and 38 +/- 11 nM, respectively). However, when mdx myotubes were exposed to a high extracellular calcium concentration ([Ca2+]c) of 40 mM, the [Ca2+]c was elevated to 84 +/- 29 nM, compared to 49 +/- 7 nM in normal myotubes. 3. Lowering the osmolarity of the superfusion solution from 300 mOsm to 100 mOsm resulted also in a rise in [Ca2+]c which was about two times higher for mdx (243 +/- 65 nM) than for C57BL10 (135 +/- 37 nM). Replacing extracellular Ca2+ by EGTA (0.2 mM) prevented the rise in [Ca2+]c in both mdx and normal myotubes when exposed to the low osmolarity solution. 4. Gadolinium ion (50 microM), an inhibitor of Ca2+ entry, antagonized the rise in [Ca2+]c of myotubes superfused with 40 mM [Ca2+]c by 20-40% for both mdx and C57BL10 cells, but did not significantly reduce the rise in [Ca2+]c when the cells were exposed to the hypo-osmotic buffer (100 mOsm). 5. Incubation of the cell culture for 3-5 days from the onset of induction of myotube formation with the membrane permeable protease inhibitor, calpeptin (50 microM) abolished the rise in [Ca2+]c in mdx myotubes upon exposure to hypo-osmotic shock. 6. Treatment of the cell culture for 3-5 days with alpha-methylprednisolone (PDN, 10 microM) attenuated the rise in [Ca2+]c following hypo-osmotic stress for both normal and mdx myotubes by about 50%. 7. The results described here suggest an increased permeability of mdx myotubes to Ca2+ under specific stress conditions. The ameliorating effect of PDN on [Ca2+]c could explain, at least partly, the beneficial effect of this drug on DMD patients.     

Effects of okadaic acid on cytosolic calcium concentrations and on contractions of the porcine coronary artery.

1. We investigated the effects of okadaic acid (OA), a phosphatase inhibitor derived from a 38-carbon fatty acid and isolated from the black sponge, genus Halichondria, on cytosolic Ca2+ concentration ([Ca2+]i) and tension developed in porcine coronary arterial strips loaded with fura-2. 2. Both in the presence (1.25 mM) and absence of extracellular Ca2+, OA (over 10(-6) M) induced a concentration-dependent, slow and progressive increase in tension. Calcium removal had no effect on the maximum level of tension, time between application of the drug and the onset of tension, or the time required to reach the maximum tension. However, there was a slight concentration-dependent increase in [Ca2+]i, only in the presence of extracellular Ca2+. 3. At a lower concentration that did not cause contraction or increase [Ca2+]i, OA (10(-6) M) inhibited tension development but not the Ca2+ transient on readmission of Ca2+ in 118 mM K+-depolarizing solution. OA inhibited the maximum levels of the developed tension, without affecting the KD value (598 +/- 204 nM for control vs 678 +/- 464 nM after OA treatment) or the Hill coefficient (1.78 +/- 0.10 for control vs 1.98 +/- 0.47 for OA treatment). 4. It is concluded that high concentrations of OA induce a contraction independent of extracellular Ca2+ and without any changes in [Ca2+]i. Lower concentrations of OA inhibit the Ca2+-dependent contractions. The lack of effect on KD values suggests that the [Ca2+]i-sensitivity of the contractile apparatus is not affected by this inhibition of contraction.     

Level of cytosolic free calcium during acetaminophen toxicity in mouse hepatocytes.

It has been suggested that elevated cytosolic free calcium plays a key role in acetaminophen-induced cell death. The present study has examined the effect of a toxic concentration of acetaminophen on cytosolic free calcium in single mouse hepatocytes, using the dye fura-2 and video imaging fluorescence microscopy. Cytosolic free calcium was calculated from the ratio of emitted fluorescence at greater than 475 nm produced by excitation at 340 and 380 nm, using a double-intensified silicon target camera and digital image processing. In the presence of 5 mM acetaminophen, cell death did not occur for 2 hr, but the toxic lesion that ultimately killed the cells occurred as early as 1 hr. If cytosolic free calcium plays an important role in these toxic events, it would be expected to increase during this period. However, during a 2-hr exposure, cytosolic free calcium concentration in cells exposed to acetaminophen was not different from control. In hepatocytes incubated for longer than 2 hr, the calcium concentration increased shortly before loss of cell viability (i.e., as a late event), consistent with an influx of calcium through a damaged cell membrane. This late increase in calcium occurred well after the appearance of cell surface blebs. The data suggest that there is no sustained change in cytosolic free calcium in acetaminophen injury either before or during the time when irreversible toxic events occur in hepatocytes.     

Somatostatin-induced control of cytosolic free calcium in pituitary tumour cells

1. In rat pituitary tumour cells (GC cells), spontaneous oscillations of the intracellular concentration of Ca2+ ([Ca2+]i) induce growth hormone (GH) secretion that is inhibited by octreotide, a somatostatin (SRIF) agonist which binds to SRIF subtype (sst) receptor 2. The effects of its functional activation on the control of [Ca2+]i were investigated using fluorimetric measurements of [Ca2+]i. 2. SRIF decreases the basal [Ca2+]i and the [Ca2+]i rise in response to forskolin (FSK) through the inhibition of L-type voltage-dependent Ca2+ channels. 3. Pretreatment with octreotide or with L-Tyr8++ Cyanamid 154806, a sst2 receptor antagonist, abolishes the SRIF-induced inhibition of [Ca2+]i. Octreotide is known to operate through agonist-induced desensitization, while the antagonist operates through receptor blockade. 4. sst1 and sst2 receptor-immunoreactivities (-IRs) are localized to cell membranes. sst2, but not sst1 receptor-IR, internalizes after cell exposure to octreotide. 5. SRIF-induced inhibition of basal [Ca2+]i or FSK-induced Ca2+ entry is blocked by pertussis toxin (PTX). 6. FSK-induced cyclic AMP accumulation is only partially decreased by SRIF or octreotide, indicating that sst2 receptors are coupled to intracellular pathways other than adenylyl cyclase (AC) inhibition. 7. In the presence of H-89, an inhibitor of cyclic AMP-dependent protein kinase (PKA), SRIF-induced inhibition of basal [Ca2+]i is still present, although reduced in amplitude. 8. SRIF inhibits [Ca2+]i by activating sst2 receptors. Inhibition of AC activity is only partly responsible for this effect, and other transduction pathways may be involved.     

Lack of changes in cytosolic ionized calcium in primary cultures of rat kidney cortical cells exposed to cytotoxic concentrations of gentamicin

Gentamicin nephrotoxicity in vivo has a delayed onset. Our assessment of gentamicin-induced cell death in vitro, by measuring the release of cytosolic lactate dehydrogenase (LDH), indicated a prolonged onset as well. A recent study, which showed that gentamicin caused an abrupt increase in the concentration of cytosolic free calcium ([Ca2+]i) in a trypsin-harvested kidney cell line, suggested that immediate changes in calcium homeostasis may initiate the pathogenesis of gentamicin nephrotoxicity. To study the immediate effect of gentamicin on [Ca2+]i, gentamicin was perfused for 1 hr over primary monolayer cultures of renal cortical epithelial cells, and suspensions of trypsin-harvested renal cells (from primary cultures and a cell line) were treated with gentamicin for 30 min. [Ca2+]i was determined using the fluorescent probe fura-2. Positive controls (ionomycin and mercury) reliably increased [Ca2+]i in each experimental model, but no increase in [Ca2+]i was observed with gentamicin. Because enzyme release data indicated that significant cytotoxicity did not occur until 48 hr of exposure to 2 mM gentamicin, primary cultures were exposed to gentamicin (1-2 mM) for 24-48 hr and [Ca2+]i was measured. No gentamicin-induced increase in [Ca2+]i was observed in these longer exposures, whether or not significant LDH release occurred. These results do not support a role for elevated [Ca2+]i in the cytotoxicity of gentamicin in cultured kidney cells, either immediately after exposure or following prolonged exposures.     

Effect of extracellular ATP on contraction,cytosolic calcium activity,membrane voltage and ion currents of rat mesangial cells in primary culture.

1. The effects of extracellular ATP on contraction, membrane voltage (Vm), ion currents and intracellular calcium activity [Ca2+]i were studied in rat mesangial cells (MC) in primary culture. 2. Addition of extracellular ATP (10(-5) and 10(-4) M) to MC led to a cell contraction which was independent of extracellular calcium. 3. Membrane voltage (Vm) and ion currents were measured with the nystatin patch clamp technique. ATP induced a concentration-dependent transient depolarization of Vm (ED50: 2 x 10(-6) M). During the transient depolarization ion currents were monitored simultaneously and showed an increase of the inward- and outward current. 4. In a buffer with a reduced extracellular chloride concentration (from 145 to 30 mM) ATP induced a depolarization augmented to -4 +/- 4 mV. 5. ATP-gamma-S and 2-methylthio-ATP depolarized Vm to the same extent as ATP, whereas alpha,beta-methylene-ATP (all 10(-5) M) had no effect on Vm. 6. The Ca2+ ionophore, A23187, depolarized Vm transiently from -51 +/- 2 to -28 +/- 4 mV and caused an increase of the inward current. 7. The intracellular calcium activity [Ca2+]i was measured with the fura-2 technique. ATP stimulated a concentration-dependent increase of [Ca2+]i (ED50: 5 x 10(-6) M). The increase of [Ca2+]i was biphasic with an initial peak followed by a sustained plateau. 8. The [Ca2+]i peak was still present in an extracellular Ca(2+)-free buffer, whereas the plateau was abolished. Verapamil (10(-4) M) did not inhibit the [Ca2+]i increase induced by ATP.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of the Chinese herb component phellopterin on the increase in cytosolic free calcium in PC12 cells

The present study investigated the effects of the Chinese Herb component, phellopterin on high K⁺ and glutamate‐induced extracellular calcium influx and caffeine or cyclopiazonic acid (CPA)‐induced calcium release from internal stores in attached PC12 cells. Attached cells were loaded with the calcium fluorescent indicator Fluo‐3/AM with the final concentration of 5 µM for 50 min at 37°C and cytosolic free Ca²⁺ measured as fluorescent intensity (FI) (excitation: 488 nm; emission: 535 nm). When PC12 cells were exposed to extracellular Ca²⁺([Ca²⁺]₀) 2.0 mM, the FI for resting [Ca²⁺]_i was 1,188±163, high K⁺ (75 mM) and glutamate (10 mM) induced an increase in [Ca²⁺]_i with peak values of 4,270±982 and 3,096±402, respectively. Phellopterin (0.1–100 µM) had no apparent effect on resting [Ca²⁺]_i, but inhibited high K⁺ and glutamate induced the increase in [Ca²⁺]_i in a dose‐dependent manner. When PC12 cells were exposed to Ca²⁺‐free solution, the FI for resting [Ca²⁺]_i was 804±77. Caffeine (40 mM) and CPA (30 µM) stimulated Ca²⁺ release from caffeine‐ryanodine and inositol 1,4,5‐tris‐phosphate (InsP₃₎‐sensitive internal calcium stores, inducing an increase in [Ca²⁺]_i to 2,938±362 and 1,816±291, respectively. Phellopterin (0.1–100 µmol/L) inhibited caffeine and CPA stimulated intracellular calcium release in a dose‐dependent manner. In summary, phellopterin, a novel component isolated from Changii radix, inhibited Ca²⁺ influx induced by stimulation of voltage‐gated and receptor‐dependent calcium channels with a greater inhibition of receptor‐dependent calcium channels. It also inhibited Ca²⁺ release from caffeine‐ryanodine and InsP₃‐sensitive internal stores, being more potent for caffeine stimulation. Phellopterin may be a promising candidate for the development of new classes of calcium antagonists. Drug Dev Res 68:79–83, 2007. © 2007 Wiley‐Liss, Inc.     

双苯氟嗪对实验性心律失常及心室肌细胞内钙浓度的影响(英文)

目的观察双苯氟嗪对实验性心律失常的作用及其可能机制。方法采用静脉灌流毒毛花苷G诱发豚鼠心律失常,心肌缺血再灌注诱发大鼠心律失常,观察双苯氟嗪的抗心律失常作用;利用激光共聚焦扫描显微镜观察双苯氟嗪对心室肌细胞内游离钙子浓度([Ca2 +]i)的影响。结果双苯氟嗪20mg·kg-1能提高毒毛花苷G诱发豚鼠室性早搏、室速、室颤和死亡的剂量;10 mg·kg-1提高诱发室性早搏的剂量。双苯氟嗪20 mg·kg-1减少心肌缺血再灌注诱发的大鼠室速、室颤发生率及动物死亡率;10mg·kg-1减少室颤发生率及动物死亡率。双苯氟嗪预先给药可降低豚鼠正常心室肌细胞[Ca2 +]i,并抑制细胞外高钙诱发的细胞[Ca2 +]i升高;在细胞外高钙已诱发细胞[Ca2 +]i升高的条件下,仍可降低[Ca2 +]i升高的程度。结论双苯氟嗪具有抗实验性心律失常作用,这种作用可能与其保持细胞内钙稳态有关。     

Alteration of cytosolic calcium levels in PC12 cells by potassium cyanide

The effect of KCN on cytosolic Ca2+ levels was measured in PC12 cells using Quin II/AM, a fluorometric calcium indicator. The resting cytosolic Ca2+ concentration, 115.0 +/- 4.9 nm, increased gradually and steadily over a 30-min time period following addition of 10(-4), 10(-3), or 10(-2)M KCN to the cells. After 15 min, 10(-3) and 10(-2)M KCN produced a three- and sixfold increase in the cytosolic Ca2+ concentration, respectively. In K+-depolarized cells, KCN induced a more rapid rise of intracellular calcium than in cells treated with KCN or KCI alone. KCN and/or K+-induced accumulation of cytosolic Ca2+ was blocked when the cells were pretreated with 10(-5)M diltiazem (a calcium channel blocker). These results demonstrate in a cell model that cyanide induces an accumulation of cytosolic Ca2+ and this additional cytosolic Ca2+ load appears to originate primarily from the extracellular compartment. This study supports previous reports implicating calcium as an intracellular mediator of cyanide toxicity.     

Effects of sodium nitroprusside on cytosolic calcium level in vascular smooth muscle

The inhibitory effect of sodium nitroprusside on the cytosolic Ca2+ level ([Ca2+]cyt), measured simultaneously with contraction by means of a fluorescence dye, fura-2, and on the 45Ca2+ uptake was tested in the isolated rat aortic smooth muscle. Norepinephrine increased muscle tension, 45Ca2+ uptake and [Ca2+]cyt. In a Ca2+-deficient solution, norepinephrine transiently increased muscle tension and [Ca2+]cyt. Sodium nitroprusside inhibited all changes induced by norepinephrine although the inhibition of [Ca2+]cyt was less than that of muscle contraction. Sodium nitroprusside also inhibited the high K+-induced contraction at concentrations higher than those needed to inhibit norepinephrine-induced contraction. Inhibition of the high K+induced contraction was accompanied by a small decrease in [Ca2+]cyt and a smaller decrease in 45Ca2+ uptake. Methylene blue antagonized, and M&B 22,948 potentiated the inhibitory effect of sodium nitroprusside. These results suggest that sodium nitroprusside has multiple sites of action. At relatively low concentrations, sodium nitroprusside could inhibit the Ca2+ influx and Ca2+ release. At relatively high concentrations, this inhibitor could also augment Ca2+ sequestration and decrease the sensitivity of contractile elements to Ca2+.     

Effects of various antipsychotic drugs upon the striatal concentrations of para-hydroxyphenylacetic acid and meta-hydroxyphenylacetic acid in the mouse.

The endogenous concentrations of p- and m-hydroxyphenylacetic acid in the mouse caudate nucleus were determined by a gas chromatographic or a gas chromatographic-mass spectrometric technique and the concentrations were about 30 and 11 ng g-1 respectively. The subcutaneous administration of (+)-butaclamol (1 mg kg-1), haloperidol (5 mg kg-1), molindone (100 mg kg-1), sulpiride (50 mg kg-1) or chlorpromazine (20 mg kg-1) increased the concentration of mouse striatal p- and m-hydroxyphenylacetic acid; the effects were observed at 2 h after drug administration. Lower doses of chlorpromazine (2 mg kg-1), haloperidol (0.2 mg kg-1) and molindone (2 mg kg-1) did not affect p- or m-hydroxyphenylacetic acid concentrations. The time course for the concentration changes produced by chlorpromazine (20 mg kg-1) revealed that the formation of the metabolites occurred within 30 min after its administration and that their efflux from the caudate nucleus took at least 4 h for p-hydroxyphenylacetic acid and more than 8 h for m-hydroxyphenylacetic acid. Promethazine and (-)-butaclamol which have chemical structures related to chlorpromazine or (+)-butaclamol respectively but which lack antipsychotic activity, produced no effect on striatal p- or m-hydroxyphenylacetic acid concentrations. The results suggest that antipsychotic drugs increase the utilization of mouse striatal p- and m-tyramine and that after use the amines are metabolized by monoamine oxidase to form p- or m-hydroxyphenylacetic acid. The synthesis of the acid metabolites occurs within 30 min after chlorpromazine administration and their efflux from the caudate nucleus takes from 4-8 h.     

细胞因子信号负调控因子3基因转染对高糖刺激下肾小球系膜细胞增殖和凋亡的影响

目的探讨细胞因子信号负调控因子(SOCS)3基因对高糖培养下人肾小球系膜细胞(HMCs)增殖、凋亡的影响。方法以脂质体为载体将PCR3.1 SOCS3转染至体外培养的HMCs,应用反转录聚合酶链反应(RT-PCR)和免疫细胞化学法鉴定转染前后细胞中SOCS3 mRNA和蛋白表达;高糖培养HMCs 12、24、48 h,采用蛋白印迹法分别检测正常对照组(CG)、高糖组(HG)、高糖+空质粒转染(HG+PV)组、高糖+SOCS3基因转染(HG+PS)组蛋白酪氨酸磷酸激酶(JAK)2、信号转导及转录活化因子(STAT)1蛋白酪氨酸磷酸化水平变化;免疫细胞化学法、末端脱氧核苷酸转移酶介导的dUTP缺口末端标记技术(TUNEL)法检测转染前后细胞增殖指数(PI)和凋亡指数(AI)。结果经鉴定,转染后HMCs中有SOCS3 mRNA和蛋白稳定表达;与CG组和HG+PV组相比,HG+PS组细胞中JAK2、STAT1蛋白酪氨酸磷酸化水平显著下降(P<0.05),PI显著减少(P<0.01),AI无明显差异。结论 SOCS3蛋白可能通过降低JAK2、STAT1酪氨酸磷酸化水平抑制HMCs增殖。     

Effects of angiotensin IV and angiotensin-(1-7) on basal and angiotensin II-stimulated cytosolic Ca2+ in mesangial cells

This study analyzed the influence of two main metabolites of angiotensin II, angiotensin IV and angiotensin-(1-7), on basal and angiotensin II-dependent [Ca2+](i) in rat mesangial cells. Angiotensin IV behaved as a weak agonist. Its effects were abolished by angiotensin AT(1) receptor antagonists. Treatment with angiotensin II abolished the effect of a subsequent treatment with angiotensin IV whereas two successive angiotensin IV-dependent [Ca2+](i) peaks were obtained. Angiotensin II increased [Ca2+](i) in a Ca2+-free medium whereas angiotensin IV was inactive. Leucine-valine-valine-hemorphin 7, a hemorphin specific for the angiotensin AT(4) receptor, was devoid of any agonistic or antagonistic effect. In contrast, angiotensin-(1-7), if without influence on basal [Ca2+](i), inhibited angiotensin II- and angiotensin IV-dependent [Ca2+](i) increases. Total inhibition of the angiotensin IV effect was obtained whereas association of angiotensin-(1-7) to 8-(NN-diethylamino)-octyl-3,4,5-trimethoxybenzoate, an inhibitor of inositol phosphate-mediated Ca2+ release, was necessary to suppress the effect of angiotensin II. These results provide evidence that angiotensin II metabolites may participate in the control of [Ca2+](i) in mesangial cells at the initial stage of binding to the angiotensin AT(1) receptors.