Kan Hong, Xie Zirong, Finkel Mitchell S
Department of Medicine, WVU Cardiology, West Virginia University School of Medicine, Medical Center Drive, Morgantown, WV 26506-9157, USA.
Am J Physiol Cell Physiol. 2004 Jan;286(1):C1-7. doi: 10.1152/ajpcell.00059.2003.
Myocardial dysfunction leading to dilated cardiomyopathy has been documented with surprisingly high frequency in human immunodeficiency virus (HIV)-infected individuals. p38 MAP kinase has been implicated as a mediator of myocardial dysfunction. We previously reported p38 MAP kinase activation by the HIV coat protein gp120 in neonatal rat cardiac myocytes. We now report the direct inotropic effects of HIV gp120 on adult rat ventricular myocytes (ARVM). ARVM were continuously superfused with gp120, and percent fractional shortening (FS) was determined by automated border detection and simultaneous intracellular ionized free Ca2+ concentration ([Ca2+]i) measured by fura 2-AM fluorescence: gp120 alone increased FS and increased [Ca2+]i within 5 min and then depressed FS without a decrease in [Ca2+]i by 20-60 min, which persisted for at least 2 h. Exposure of ARVM to gp120 also resulted in the phosphorylation of the upstream regulator of p38 MAP kinase MKK3/6, p38 MAP kinase itself, and its downstream effector, ATF-2, over a similar time course. ERK (p44/42) and JNK stress signaling pathways were not similarly activated. The effects of the p38 MAP kinase inhibitor were concentration dependent. SB-203580 (10 microM) blocked both p38 MAP kinase phosphorylation and the delayed negative inotropic effect of gp120. SB-203580 (5 microM) selectively blocked phosphorylation of ATF-2 without blocking the phosphorylation of MKK3/6 or p38 MAP kinase itself. SB-203580 (5 microM) administered before, with, or after gp120 blocked the negative inotropic effect of gp120 in ARVM. p38 MAP kinase activation may be a common stress-response mechanism contributing to myocardial dysfunction in HIV and other nonischemic as well as ischemic cardiomyopathies.
在人类免疫缺陷病毒（HIV）感染个体中，导致扩张型心肌病的心肌功能障碍已被证实具有惊人的高发生率。p38丝裂原活化蛋白激酶（p38 MAP激酶）被认为是心肌功能障碍的介质。我们之前报道过HIV包膜蛋白gp120可激活新生大鼠心肌细胞中的p38 MAP激酶。我们现在报道HIV gp120对成年大鼠心室肌细胞（ARVM）的直接变力作用。用gp120持续灌流ARVM，通过自动边界检测确定分数缩短百分比（FS），并用fura 2-AM荧光法同步测量细胞内游离钙离子浓度（[Ca2+]i）：单独使用gp120可使FS增加，并在5分钟内使[Ca2+]i升高，然后在20 - 60分钟时使FS降低，但[Ca2+]i并未下降，这种情况持续至少2小时。将ARVM暴露于gp120还会在相似的时间进程中导致p38 MAP激酶的上游调节因子MKK3/6、p38 MAP激酶本身及其下游效应物ATF-2发生磷酸化。细胞外调节蛋白激酶（ERK，p44/42）和应激活化蛋白激酶（JNK）应激信号通路未被类似激活。p38 MAP激酶抑制剂的作用呈浓度依赖性。SB-203580（10微摩尔）可阻断p38 MAP激酶的磷酸化以及gp120的延迟负性变力作用。SB-203580（5微摩尔）可选择性地阻断ATF-2的磷酸化，而不阻断MKK3/6或p38 MAP激酶本身的磷酸化。在给予gp120之前、同时或之后给予SB-203580（5微摩尔）均可阻断gp120对ARVM的负性变力作用。p38 MAP激酶激活可能是一种常见的应激反应机制，在HIV以及其他非缺血性和缺血性心肌病中导致心肌功能障碍。
