Cellular Mechanisms of Vasoregulation by Volatile Anesthetics

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DESCRIPTION (provided by applicant): Two-pore-domain K+channels (K2P-channels) represent targets for actions of inhalation anesthetics on neurons. The few reports characterizing K2P channels in vascular beds are from pulmonary and mesenteric arteries. We have recently found that ATP stimulates K+current that is resistant to major K+channel blockers and sensitive to pH and Zn. Furthermore, our preliminary data suggest that this current is through K2P channels and that these channels may regulate vessel diameter. This is a novel finding that positions K2P channels as potential targets of inhalation anesthetics in cerebral arteries. Our overall working hypothesis is that volatile anesthetics activate K2P channels in vascular myocytes and thereby dilate arteries. Inhalation anesthetics will activate K2P channels depending on their open probability. Using a combination of electrophysiological, pharmacological, imaging and vessel tension measurements, we will test this hypothesis in the following specific aims. Specific Aim 1: To determine pharmacology of blockers-resistive K2P-like currents in thoracic aorta and middle cerebral artery. In this aim, we propose to prove by pharmacological tools that blockers resistive whole cell outward current inhibited by acidic and stimulated basic pH has K+selectivity and is carried by K2P-like channels. 1) Do known K2P-channel blockers decrease amplitude of leak K+currents in myocytes isolated from thoracic aorta and middle cerebral artery? 2) What part of the resting membrane potential is determined by opening of K2P-like channels in vascular myocytes? 3) What is the impact of K2P channel blockers on vessel diameter? Specific Aim 2: To determine how inhalation anesthetics activate K2P-like channels and the impact of inhalation anesthetics on vascular tone? We will use a combination of electrophysiology, pharmacology, and vessel tension measurements to answer the questions: 1) Do general anesthetics increase the amplitude of K2P channel currents? 2) What is the impact of K2P channel activation by general anesthetics on vessel diameter? 3) Can inhalational anesthetics potentiate ATP-elicited vascular responses? The results of these studies will describe a novel signaling pathway regulating vascular tone through K2P channels. Pharmacological characterization of region specific K2P channels should lead to new targeted treatments of hypertension and stroke and will be of benefit for general anesthesia. PUBLIC HEALTH RELEVANCE: Cardiovascular disease, hypertension and stroke are leading causes of death in the U.S. The present proposal will investigate a novel signaling pathway to regulate vascular tone via K2P channels. Pharmacological characterization of region specific K2P channels (middle cerebral artery and aorta) should lead to new targeted treatments of hypertension and stroke. These types of studies will validate cellular mechanisms of anesthetic action and could be used to develop a possible treatment protocol.