Rivet-Bastide M, Vandecasteele G, Hatem S, Verde I, Bénardeau A, Mercadier J J, Fischmeister R
Laboratoire de Cardiologie Cellulaire et Moléculaire, Institut National de la Santé et de la Recherche Médicale U-446, Université de Paris-Sud, Faculté de Pharmacie, F-92296 Châtenay-Malabry, France.
J Clin Invest. 1997 Jun 1;99(11):2710-8. doi: 10.1172/JCI119460.
EHNA (Erythro-9-[2-hydroxy-3-nonyl]adenine) is a wellknown inhibitor of adenosine deaminase. Recently, EHNA was shown to block the activity of purified soluble cGMPstimulated phosphodiesterase (PDE2) from frog, human, and porcine heart with an apparent Ki value of approximately 1 microM and with negligible effects on Ca2+/calmodulin PDE (PDE1), cGMP-inhibited PDE (PDE3), and low Km cAMP-specific PDE (PDE4) (Méry, P.F., C. Pavoine, F. Pecker, and R. Fischmeister. 1995. Mol. Pharmacol. 48:121-130; Podzuweit, T., P. Nennstiel, and A. Muller. 1995. Cell. Signalling. 7:733- 738). To investigate the role of PDE2 in the regulation of cardiac L-type Ca2+ current (ICa), we have examined the effect of EHNA on ICa in freshly isolated human atrial myocytes. Extracellular application of 0.1-10 microM EHNA induced an increase in the amplitude of basal ICa ( approximately 80% at 1 microM) without modification of the current-voltage or inactivation curves. The maximal stimulatory effect of EHNA on ICa was comparable in amplitude with the maximal effect of isoprenaline (1 microM), and the two effects were not additive. The effect of EHNA was not a result of adenosine deaminase inhibition, since 2'-deoxycoformycin (1-30 microM), another adenosine deaminase inhibitor with no effect on PDE2, or adenosine (1-10 microM) did not increase ICa. In the absence of intracellular GTP, the substrate of guanylyl cyclase, EHNA did not increase ICa. However, under similar conditions, intracellular perfusion with 0.5 microM cGMP produced an 80% increase in ICa. As opposed to human cardiomyocytes, EHNA (1-10 microM) did not modify ICa in isolated rat ventricular and atrial myocytes. We conclude that basal ICa is controlled by PDE2 activity in human atrial myocytes. Both PDE2 and PDE3 may contribute to keep the cyclic nucleotides concentrations at minimum in the absence of adenylyl and/or guanylyl cyclase stimulation.
EHNA（赤藓红-9-[2-羟基-3-壬基]腺嘌呤）是一种著名的腺苷脱氨酶抑制剂。最近研究表明，EHNA能抑制纯化的来自青蛙、人类和猪心脏的可溶性环鸟苷酸刺激的磷酸二酯酶（PDE2）的活性，其表观抑制常数（Ki）约为1微摩尔，对钙离子/钙调蛋白磷酸二酯酶（PDE1）、环鸟苷酸抑制的磷酸二酯酶（PDE3）和低Km值的环磷酸腺苷特异性磷酸二酯酶（PDE4）影响可忽略不计（梅里，P.F.，C. 帕瓦因，F. 佩克，和R. 菲施迈斯特。1995年。《分子药理学》48:121 - 130；波祖维特，T.，P. 嫩斯提尔，和A. 米勒。1995年。《细胞信号传导》7:733 - 738）。为研究PDE2在调节心脏L型钙电流（ICa）中的作用，我们检测了EHNA对新鲜分离的人心房肌细胞中ICa的影响。细胞外给予0.1 - 10微摩尔的EHNA可使基础ICa的幅度增加（1微摩尔时约增加80%），而不改变电流-电压曲线或失活曲线。EHNA对ICa的最大刺激作用在幅度上与异丙肾上腺素（1微摩尔）的最大作用相当，且两种作用无叠加效应。EHNA的作用并非腺苷脱氨酶抑制的结果，因为2'-脱氧助间型霉素（1 - 30微摩尔），另一种对PDE2无作用的腺苷脱氨酶抑制剂，以及腺苷（1 - 10微摩尔）均未增加ICa。在缺乏鸟苷酸环化酶的底物细胞内三磷酸鸟苷（GTP）时，EHNA不会增加ICa。然而，在类似条件下，细胞内灌注0.5微摩尔环鸟苷酸可使ICa增加80%。与人心肌细胞不同，EHNA（1 - 10微摩尔）对分离的大鼠心室和心房肌细胞中的ICa无影响。我们得出结论，基础ICa在人心房肌细胞中受PDE2活性控制。在不存在腺苷酸环化酶和/或鸟苷酸环化酶刺激时，PDE2和PDE3可能共同作用使环核苷酸浓度保持在最低水平。
