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Stretch-activation of angiotensin II type 1a receptors contributes to the myogenic response of mouse mesenteric and renal arteries #MMPMID24838176
Schleifenbaum J; Kassmann M; Szijarto IA; Hercule HC; Tano JY; Weinert S; Heidenreich M; Pathan AR; Anistan YM; Alenina N; Rusch NJ; Bader M; Jentsch TJ; Gollasch M
Circ Res 2014[Jul]; 115 (2): 263-72 PMID24838176show ga
RATIONALE: Vascular wall stretch is the major stimulus for the myogenic response of small arteries to pressure. The molecular mechanisms are elusive, but recent findings suggest that G protein-coupled receptors can elicit a stretch response. OBJECTIVE: To determine whether angiotensin II type 1 receptors (AT1R) in vascular smooth muscle cells exert mechanosensitivity and identify the downstream ion channel mediators of myogenic vasoconstriction. METHODS AND RESULTS: We used mice deficient in AT1R signaling molecules and putative ion channel targets, namely AT1R, angiotensinogen, transient receptor potential channel 6 (TRPC6) channels, or several subtypes of the voltage-gated K+ (Kv7) gene family (KCNQ3, 4, or 5). We identified a mechanosensing mechanism in isolated mesenteric arteries and in the renal circulation that relies on coupling of the AT1R subtype a to a Gq/11 protein as a critical event to accomplish the myogenic response. Arterial mechanoactivation occurs after pharmacological block of AT1R and in the absence of angiotensinogen or TRPC6 channels. Activation of AT1R subtype a by osmotically induced membrane stretch suppresses an XE991-sensitive Kv channel current in patch-clamped vascular smooth muscle cells, and similar concentrations of XE991 enhance mesenteric and renal myogenic tone. Although XE991-sensitive KCNQ3, 4, and 5 channels are expressed in vascular smooth muscle cells, XE991-sensitive K+ current and myogenic contractions persist in arteries deficient in these channels. CONCLUSIONS: Our results provide definitive evidence that myogenic responses of mouse mesenteric and renal arteries rely on ligand-independent, mechanoactivation of AT1R subtype a. The AT1R subtype a signal relies on an ion channel distinct from TRPC6 or KCNQ3, 4, or 5 to enact vascular smooth muscle cell activation and elevated vascular resistance.
|4-Aminopyridine/pharmacology[MESH]
|Angiotensin II Type 1 Receptor Blockers/pharmacology[MESH]
|Animals[MESH]
|Anthracenes/pharmacology[MESH]
|GTP-Binding Protein alpha Subunits, Gq-G11/physiology[MESH]
|HEK293 Cells[MESH]
|Hemorheology[MESH]
|Humans[MESH]
|KCNQ Potassium Channels/physiology[MESH]
|KCNQ3 Potassium Channel/physiology[MESH]
|Losartan/pharmacology[MESH]
|Mesenteric Arteries/cytology/*physiology[MESH]
|Mice[MESH]
|Mice, Inbred C57BL[MESH]
|Mice, Knockout[MESH]
|Myocytes, Smooth Muscle/*physiology[MESH]
|Osmotic Pressure[MESH]
|Pressoreceptors/*physiology[MESH]
|Receptor, Angiotensin, Type 1/deficiency/genetics/*physiology[MESH]