Received 2002-04-02 Accepted 2002-05-24
*Corresponding author. Tel: +86-311-6062490; Fax: +86-311-6062490; E-mail: syho@Hebmu.edu.cn
Effect of agmatine on free intracellular calcium concentration in isolated rat ventricular myocytes
LI Qing1, SHANG Zhong-Lin2, YIN Jing-Xiang1, WANG Yi-He3, HE Rui-Rong1 *
1Department
of Physiology,
2College
of Life Science,
3Department
of Physiology,
Abstract: The present study was to investigate the
effects of agmatine (Agm)
on free intracellular calcium concentration ([Ca2+]i) of isolated rat ventricular myocytes. [Ca2+]i was measured by confocal
microscopy in single rat ventricular myocytes which
were dissociated by enzymatic dissociation method and loaded with Fluo 3-AM. The
changes in [Ca2+]i were
represented by fluorescence intensity (FI) or relative fluorescence intensity
(F/F0%). The results showed that the control level of FI value of single rat
ventricular myocytes was 128.8±13.8 and 119.6±13.6
in the presence of normal Tyrode's solution
containing Ca2+ 1.0 mmol/L and Ca2+-free Tyrode's
solution, respectively. There was
no difference between these two groups (P>0.05). Agm 0.1, 1,
and 10 mmol/L significantly reduced the [Ca2+]i in both extracellular solutions
in a concentration-dependent manner. The similar effect of Agm
on [Ca2+]i was also observed
in the presence of EGTA 3 mmol/L. KCl 60 mmol/L, PE 30 μmol/L,
and Bay-K-8644 10 μmol/L, all these substances induced [Ca2+]i elevations in ventricular myocytes. Agm (0.1, 1,
and 10 mmol/L) markedly inhibited the increase in [Ca2+]i induced by KCl, phenylephrine (PE), and Bay-K-8644. When Ca2+ waves were produced by
increasing extracellular Ca2+ concentration from 1 to
10 mmol/L, 1
mmol/L
Agm could block the propagating waves of
elevated [Ca2+]i, and reduce the velocity and
duration of propagating waves.
These results suggest that Agm possesses an
inhibitory effects on [Ca2+]i
via blocking voltage-dependent Ca2+ channel, and possibly by alleviating calcium
release from SR in single isolated rat ventricular myocytes.
Key
words: agmatine; fluorescence intensity; myocytes; intracellular calcium; Ca2+ channel;
intracellular
Ca2+
release; confocal microscopy
胍丁胺对大鼠心室肌细胞内游离钙浓度的影响
李清1, 尚忠林2, 尹京湘1, 王义和3, 何瑞荣1,
1河北医科大学基础医学研究所生理室, 石家庄 050017;
2河北师范大学生命科学院, 石家庄 050016;
3中国人民武警医学院生理教研室, 天津 300162
摘要: 本研究旨在观察胍丁胺(agmatine, Agm) 对分离大鼠心室肌细胞内游离钙浓度([Ca2+]i)的影响。用酶解方法分离大鼠心室肌细胞,
用Fluo 3-AM负载, 然后用激光共聚焦法测定单个心室肌细胞[Ca2+]i的荧光强度(fluorescence intensity, FI), 结果以FI 或相对荧光强度(F/F0%)表示。实验结果表明, 在正常台氏液(含钙
1.0 mmol/L)和无钙台氏液中, 单个大鼠心室肌细胞的荧光密度分别为128.8±13.8和119.6±13.6, 两者无差异。Agm 0.1、
1和10 mmol/L浓度依赖性地显著降低细胞的钙浓度; 在正常台氏液中加入EGTA 3
mmol/L, Agm同样降低细胞的钙浓度。KCl 60
mmol/L, PE 30 μmol/L,
和Bay-K-8644 10 μmol/L均升高心室肌细胞的[Ca2+]i。 Agm同样降低高浓度KCl、 Bay-K-8644和PE诱发的心室肌细胞[Ca2+]i升高。当细胞外液钙浓度由1
mmol/L增加到10 mmol/L时, 诱发心室肌细胞钙超载, 同时部分心室肌细胞产生可传播的钙波（Ca2+ wave）,
Agm 1
mmol/L 降低钙波的传播速度和持续时间, 最终阻断钙波。以上结果提示, Agm 对心室肌细胞的胞浆[Ca2+]i 具有抑制作用, 此作用通过阻断电压依赖性钙通道而实现; 并可能与抑制大鼠心室肌细胞内钙释放有关。
关键词: 胍丁胺;
荧光密度; 心室肌细胞; 细胞内钙; 钙通道;
钙释放; 共聚焦显微镜
中图分类号: Q463