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KMID : 0358619930270020151
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Korean Journal of Physiology
1993 Volume.27 No. 2 p.151 ~ p.162
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Effect of Cyclic GMP on the Calcium Current in Rabbit Ventricular Myocytes
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Han Jin
Leem Chae-Hun
Ahn Chul-Soo
So In-Suk
Kim Eui-Yong
Ho Won-Kyung
Earm Yung-E
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Abstract
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In order to investigate the effect of intracellular cyclic GMP on calcium current the whole-cell patch clamp technique with internal perfusion method was used in isolated ventricular myocytes of the rabbit. Cyclic GMP, 8-bromo-cyclic GMP, cyclic AMP, isoprenaline and forskolin were perfused into cells and their effects on calcium current were analysed by applying depolarizing step pulses of + 10 mV in amplitude far 300 msec from holding potential of - 40 mV. Not only cyclic AMP but also cyclic GMF increased the basal calcium current. 8-Bromo-cyclic GMP , a good stimulator of the cyclic GMP-dependent protein kinase, also increased the basal calcium current and its peak amplitude of calcium current was larger than that in the presence of cyclic AMP or cyclic GMP alone. In the presence of cyclic GMP or 8-bromo-cyclic GMP, already augmented calcium current was potentiated by intracellular application of cyclic AMP or isoprenaline or forskolin. In the presence of cyclic GMP, acetylcholine reduced the calcium current only when the calcium current was increased by isoprenaline. From the above results it could be concluded that intracellular perfusion with cyclic GMP increases the basal calcium current via a mechanism involving a cyclic GMP-dependent protein kinase.
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KEYWORD
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Ventricular myocytes, Whole-cell patch clamp, Calcium current, Cyclic GMP, 8-Bromo-cy-clic GMP, Cyclic GMP-dependent protein kinase
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