REGULATION OF CORONARY ARTERY MYOGENIC TONE BY PKG

维持充足的冠状动脉血流量对生命至关重要。一氧化氮(NO)可能通过对抗血管平滑肌(VSM)的收缩和限制冠状动脉张力的发展而在血流调节中发挥关键作用。事实上，循环雌激素对绝经前女性的心脏保护作用被认为至少部分是由于冠状动脉内皮细胞NO释放的增强。人们普遍认为，NO的血管舒缩作用主要是通过cGMP依赖的蛋白激酶(PKG)在平滑肌细胞中的作用来实现的。然而，主要由于缺乏具有足够选择性的抑制剂，PKG在调节血管张力中的作用尚不清楚。佛蒙特大学沃尔冈·多斯特曼博士的实验室最近开发了新的PKG多肽抑制剂，可能提供识别PKG依赖所需的选择性工具。这些多肽由有效的、底物竞争的PKG抑制物序列组成，这些抑制物序列与载体序列(通常被称为“特洛伊木马”多肽)相连，促进细胞摄取。最近的初步研究表明，新型的PKG抑制肽DT-3有效地渗透到培养的血管平滑肌细胞中，并选择性地抑制PKG的活性。在这个项目中，包括DT-3在内的特定的PKG抑制剂将被用来评估PKG作用的作用，随后将主要关注PKG依赖的钙敏感钾通道(K/Ca)的激活。这项研究的发现将为决定心脏血流量的基本机制提供有价值的见解。

Maintenance of adequate coronary artery blood flow is essential for life. Nitric oxide (NO) may play a critical role in the regulation of flow by opposing vascular smooth muscle (VSM) contraction and restricting the development of coronary artery tone. In fact, enhanced tonic release of NO from coronary endothelium is believed to account, at least in part, for the cardioprotective effect of circulating estrogen in premenopausal women. It is widely believed that the vasodillatory influence of NO is mediated predominantly through the action of cGMP dependent protein kinase (PKG) in smooth muscle cells. However, due primarily to the lack of adequately selective inhibitors, the contribution of PKG to the regulation of vascular tone remains unclear.. New peptide inhibitors of PKG, recently developed in the laboratory of Dr. Wolgang Dostmann at the University of Vermont, may provide the selective tools needed to discern PKG dependence. These peptides are composed of potent, substrate-competitive PKG inhibitor sequences linked to carrier sequences (often referred to as "Trojan horse" peptides) that facilitate cellular uptake. Recent preliminary studies have revealed that the novel PKG inhibitor peptide, DT-3, effectively permeates cultured vascular smooth muscle cells and selectively inhibits PKG activity. In this project, specific PKG inhibitors including DT-3 will be employed to assess the role of PKG action will subsequently be addressed, primarily focusing on PKG dependent activation of Ca2+ sensitive potassium channels (K/Ca). The findings of this study will provide valuable insights into the fundamental mechanisms that determine cardiac blood flow.