Li Qing, Shang Zhong-Lin, Yin Jing-Xiang, Wang Yi-He, He Rui-Rong
Department of Physiology, Hebei Medical University, Shijiazhuang 050017.
Sheng Li Xue Bao. 2002 Dec 25;54(6):467-72.
The present study was to investigate the effects of agmatine (Agm) on free intracellular calcium concentration (Ca(2+)) of isolated rat ventricular myocytes. Ca(2+) 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 Ca(2+) were represented by fluorescence intensity (FI) or relative fluorescence intensity (F/F(0)%). 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 Ca(2+) 1.0 mmol/L and Ca(2+)-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 Ca(2+) in both extracellular solutions in a concentration-dependent manner. The similar effect of Agm on Ca(2+) was also observed in the presence of EGTA 3 mmol/L. KCl 60 mmol/L, PE 30 micromol/L, and Bay-K-8644 10 micromol/L, all these substances induced Ca(2+) elevations in ventricular myocytes. Agm (0.1, 1, and 10 mmol/L) markedly inhibited the increase in Ca(2+) induced by KCl, phenylephrine (PE), and Bay-K-8644. When Ca(2+) waves were produced by increasing extracellular Ca(2+) concentration from 1 to 10 mmol/L, 1 mmol/L Agm could block the propagating waves of elevated Ca(2+), and reduce the velocity and duration of propagating waves. These results suggest that Agm possesses an inhibitory effects on Ca(2+) via blocking voltage-dependent Ca(2+) channel, and possibly by alleviating calcium release from SR in single isolated rat ventricular myocytes.
本研究旨在探讨胍丁胺（Agm）对分离的大鼠心室肌细胞胞内游离钙浓度（Ca(2+)）的影响。采用酶解法分离大鼠单个心室肌细胞，并用Fluo 3-AM进行负载，通过共聚焦显微镜测量Ca(2+)。Ca(2+)的变化用荧光强度（FI）或相对荧光强度（F/F(0)%）表示。结果显示，在含有1.0 mmol/L Ca(2+)的正常台氏液和无Ca(2+)台氏液中，单个大鼠心室肌细胞的FI值对照水平分别为128.8±13.8和119.6±13.6。两组之间无差异（P>0.05）。0.1、1和10 mmol/L的Agm在两种细胞外溶液中均以浓度依赖的方式显著降低Ca(2+)。在存在3 mmol/L EGTA的情况下，也观察到了Agm对Ca(2+)的类似作用。60 mmol/L KCl、30 μmol/L去氧肾上腺素（PE）和10 μmol/L Bay-K-8644均可诱导心室肌细胞Ca(2+)升高。Agm（0.1、1和10 mmol/L）显著抑制KCl、去氧肾上腺素（PE）和Bay-K-8644诱导的Ca(2+)升高。当细胞外Ca(2+)浓度从1 mmol/L增加到10 mmol/L产生Ca(2+)波时，1 mmol/L Agm可阻断Ca(2+)升高的传播波，并降低传播波的速度和持续时间。这些结果表明，Agm通过阻断电压依赖性Ca(2+)通道对Ca(2+)具有抑制作用，并且可能通过减轻单个分离的大鼠心室肌细胞中肌浆网的钙释放来发挥作用。
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