Barouch Lili A, Harrison Robert W, Skaf Michel W, Rosas Gisele O, Cappola Thomas P, Kobeissi Zoulficar A, Hobai Ion A, Lemmon Christopher A, Burnett Arthur L, O'Rourke Brian, Rodriguez E Rene, Huang Paul L, Lima João A C, Berkowitz Dan E, Hare Joshua M
Department of Medicine (Cardiology Division), The Johns Hopkins Medical Institutions, Baltimore, Maryland 21287, USA.
Nature. 2002 Mar 21;416(6878):337-9. doi: 10.1038/416337a.
Subcellular localization of nitric oxide (NO) synthases with effector molecules is an important regulatory mechanism for NO signalling. In the heart, NO inhibits L-type Ca2+ channels but stimulates sarcoplasmic reticulum (SR) Ca2+ release, leading to variable effects on myocardial contractility. Here we show that spatial confinement of specific NO synthase isoforms regulates this process. Endothelial NO synthase (NOS3) localizes to caveolae, where compartmentalization with beta-adrenergic receptors and L-type Ca2+ channels allows NO to inhibit beta-adrenergic-induced inotropy. Neuronal NO synthase (NOS1), however, is targeted to cardiac SR. NO stimulation of SR Ca2+ release via the ryanodine receptor (RyR) in vitro, suggests that NOS1 has an opposite, facilitative effect on contractility. We demonstrate that NOS1-deficient mice have suppressed inotropic response, whereas NOS3-deficient mice have enhanced contractility, owing to corresponding changes in SR Ca2+ release. Both NOS1-/- and NOS3-/- mice develop age-related hypertrophy, although only NOS3-/- mice are hypertensive. NOS1/3-/- double knockout mice have suppressed beta-adrenergic responses and an additive phenotype of marked ventricular remodelling. Thus, NOS1 and NOS3 mediate independent, and in some cases opposite, effects on cardiac structure and function.
一氧化氮（NO）合酶与效应分子的亚细胞定位是NO信号传导的重要调节机制。在心脏中，NO抑制L型Ca2+通道，但刺激肌浆网（SR）Ca2+释放，从而对心肌收缩力产生不同影响。在此我们表明，特定NO合酶亚型的空间限制调节了这一过程。内皮型NO合酶（NOS3）定位于小窝，在那里与β-肾上腺素能受体和L型Ca2+通道分隔，使NO能够抑制β-肾上腺素能诱导的心肌收缩力。然而，神经元型NO合酶（NOS1）靶向心肌SR。体外实验表明，NO通过兰尼碱受体（RyR）刺激SR Ca2+释放，提示NOS1对收缩力有相反的促进作用。我们证明，NOS1缺陷小鼠的变力反应受到抑制，而NOS3缺陷小鼠的收缩力增强，这是由于SR Ca2+释放的相应变化所致。尽管只有NOS3缺陷小鼠患有高血压，但NOS1-/-和NOS3-/-小鼠均出现与年龄相关的心肌肥厚。NOS1/3-/-双敲除小鼠的β-肾上腺素能反应受到抑制，并具有明显心室重塑的叠加表型。因此，NOS1和NOS3对心脏结构和功能介导独立且在某些情况下相反的作用。
