PDF(Pubmed)
Abstract：
UNASSIGNED: Upregulation of Ca2+/calmodulin-dependent protein kinase II (CaMKII) contributes to the pathogenesis of cardiovascular disease, including hypertension. Transgenic rats expressing the human angiotensinogen gene [TGR (hAGT)L1623] are a new novel humanized model of hypertension that associates with declines in cardiac contractile function and β-adrenergic receptor (AR) reserve. The molecular mechanisms are unclear. We tested the hypothesis that in TGR (hAGT)L1623 rats, left ventricular (LV) myocyte CaMKIIδ and β3-AR are upregulated, but β1-AR is down-regulated, which are important causes of cardiac dysfunction and β-AR desensitization.
UNASSIGNED: We compared LV myocyte CaMKIIδ, CaMKIIδ phosphorylation (at Thr287) (pCaMKIIδ), and β1-and β3-AR expressions and determined myocyte functional and [Ca2+]I transient ([Ca2+]iT) responses to β-AR stimulation with and without pretreatment of myocytes using an inhibitor of CaMKII, KN-93 (10-6 M, 30 min) in male Sprague Dawley (SD; N = 10) control and TGR (hAGT)L1623 (N = 10) adult rats.
UNASSIGNED: Hypertension in TGR (hAGT)L1623 rats was accompanied by significantly increased LV myocyte β3-AR protein levels and reduced β1-AR protein levels. CaMKIIδ phosphorylation (at Thr287), pCaMKIIδ was significantly increased by 35%. These changes were followed by significantly reduced basal cell contraction (dL/dtmax), relaxation (dR/dtmax), and [Ca2+]iT. Isoproterenol (10-8 M) produced significantly smaller increases in dL/dtmax, dR/dtmax, and [Ca2+]iT. Moreover, only in TGR (hAGT)L1623 rats, pretreatment of LV myocytes with KN-93 (10-6 M, 30 min) fully restored normal basal and isoproterenol-stimulated myocyte contraction, relaxation, and [Ca2+]iT.
UNASSIGNED: LV myocyte CaMKIIδ overactivation with associated contrast changes in β3-AR and β1-AR may be the key molecular mechanism for the abnormal contractile phenotype and β-AR desensitization in this humanized model of hypertension.
UNASSIGNED: We compared LV myocyte CaMKIIδ, CaMKIIδ phosphorylation (at Thr287) (pCaMKIIδ), and β1-and β3-AR expressions and determined myocyte functional and [Ca2+]I transient ([Ca2+]iT) responses to β-AR stimulation with and without pretreatment of myocytes using an inhibitor of CaMKII, KN-93 (10-6 M, 30 min) in male Sprague Dawley (SD; N = 10) control and TGR (hAGT)L1623 (N = 10) adult rats.
UNASSIGNED: Hypertension in TGR (hAGT)L1623 rats was accompanied by significantly increased LV myocyte β3-AR protein levels and reduced β1-AR protein levels. CaMKIIδ phosphorylation (at Thr287), pCaMKIIδ was significantly increased by 35%. These changes were followed by significantly reduced basal cell contraction (dL/dtmax), relaxation (dR/dtmax), and [Ca2+]iT. Isoproterenol (10-8 M) produced significantly smaller increases in dL/dtmax, dR/dtmax, and [Ca2+]iT. Moreover, only in TGR (hAGT)L1623 rats, pretreatment of LV myocytes with KN-93 (10-6 M, 30 min) fully restored normal basal and isoproterenol-stimulated myocyte contraction, relaxation, and [Ca2+]iT.
UNASSIGNED: LV myocyte CaMKIIδ overactivation with associated contrast changes in β3-AR and β1-AR may be the key molecular mechanism for the abnormal contractile phenotype and β-AR desensitization in this humanized model of hypertension.
摘要：
■Ca2+/钙调蛋白依赖性蛋白激酶II(CaMKII)上调有助于心血管疾病的发病机制,包括高血压.表达人血管紧张素原基因[TGR（hAGT）L1623]的转基因大鼠是一种新型的人源化高血压模型，与心脏收缩功能和β-肾上腺素能受体（AR）储备的下降有关。分子机制尚不清楚。我们检验了在TGR(hAGT)L1623大鼠中，左心室（LV）心肌细胞CaMKIIδ和β3-AR上调，但β1-AR下调,是导致心功能不全和β-AR脱敏的重要原因。
■我们比较了左心室肌细胞CaMKIIδ，CaMKIIδ磷酸化（在Thr287处）（pCaMKIIδ），以及β1-和β3-AR的表达，并确定了使用CaMKII抑制剂预处理和不预处理心肌细胞对β-AR刺激的心肌细胞功能和[Ca2]I瞬时（[Ca2]iT）反应，KN-93(10-6米,30分钟）在雄性SpragueDawley（SD；N=10）对照和TGR（hAGT）L1623（N=10）成年大鼠中。
■TGR（hAGT）L1623大鼠的高血压伴随着LV心肌细胞β3-AR蛋白水平的显着升高和β1-AR蛋白水平的降低。CaMKIIδ磷酸化（在Thr287），pCaMKIIδ显著增加35%。这些变化伴随着显著降低的基底细胞收缩（dL/dtmax），弛豫(dR/dtmax)，和[Ca2+]iT。异丙肾上腺素（10-8M）在dL/dtmax中产生明显较小的增加，dR/dtmax,和[Ca2+]iT。此外，仅在TGR（hAGT）L1623大鼠中，用KN-93（10-6M，30分钟）完全恢复了正常的基础和异丙肾上腺素刺激的心肌细胞收缩，放松,和[Ca2+]iT。
■LV心肌细胞CaMKIIδ过度激活以及β3-AR和β1-AR的相关对比变化可能是这种人源化高血压模型中异常收缩表型和β-AR脱敏的关键分子机制。
■我们比较了左心室肌细胞CaMKIIδ，CaMKIIδ磷酸化（在Thr287处）（pCaMKIIδ），以及β1-和β3-AR的表达，并确定了使用CaMKII抑制剂预处理和不预处理心肌细胞对β-AR刺激的心肌细胞功能和[Ca2]I瞬时（[Ca2]iT）反应，KN-93(10-6米,30分钟）在雄性SpragueDawley（SD；N=10）对照和TGR（hAGT）L1623（N=10）成年大鼠中。
■TGR（hAGT）L1623大鼠的高血压伴随着LV心肌细胞β3-AR蛋白水平的显着升高和β1-AR蛋白水平的降低。CaMKIIδ磷酸化（在Thr287），pCaMKIIδ显著增加35%。这些变化伴随着显著降低的基底细胞收缩（dL/dtmax），弛豫(dR/dtmax)，和[Ca2+]iT。异丙肾上腺素（10-8M）在dL/dtmax中产生明显较小的增加，dR/dtmax,和[Ca2+]iT。此外，仅在TGR（hAGT）L1623大鼠中，用KN-93（10-6M，30分钟）完全恢复了正常的基础和异丙肾上腺素刺激的心肌细胞收缩，放松,和[Ca2+]iT。
■LV心肌细胞CaMKIIδ过度激活以及β3-AR和β1-AR的相关对比变化可能是这种人源化高血压模型中异常收缩表型和β-AR脱敏的关键分子机制。
