Angiotensin II Stimulates Extracellular Signal–Regulated Kinase Activity in Intact Pressurized Rat Mesenteric Resistance Arteries

Abstract

Abstract-The activation of extracellular signal-regulated kinases 1/2 (ERK1/2) was assessed in isolated rat mesenteric resistance arteries (200-m diameter) in a pressure myograph and stimulated for 5 minutes by angiotensin II (Ang II, 0.1 mol/L) with a pressure of 70 mm Hg. ERK1/2 activity was measured by using an in-gel assay, and ERK1/2 phosphorylation was measured by Western blot analysis with use of a phospho-specific ERK1/2 antibody. Ang II (0.1 mol/L) induced contraction (28% of phenylephrine contraction, 10 mol/L). ERK kinase inhibitor PD98059 (10 mol/L) attenuated this contraction by 36% but not that to phenylephrine or K ϩ (60 mmol/L). In unpressurized arteries, Ang II increased ERK1/2 activity by 26%, and pressure (70 mm Hg) itself increased ERK1/2 activity by 72%. Ang II and pressure together acted synergistically, increasing ERK1/2 activity by 264%. Thus, in pressurized vessels, Ang II (0.1 mol/L) increased ERK1/2 activity by 112%, calculated as [(364/172)Ϫ1]ϫ100, which was confirmed by a measured 72% increase in ERK1/2 phosphorylation. Ang II type 1 receptor blockade by candesartan (10 mol/L) abolished the Ang II-induced increase in ERK1/2 activity, but Ang II type 2 receptor blockade (PD123319, 10 mol/L) did not. The Ang II-induced increase in ERK1/2 activity was inhibited by protein kinase C inhibitors Ro-31-8220 (1 mol/L) and Go-6976 (300 nmol/L) and tyrosine kinase inhibitors genistein (1 mol/L, general) and herbimycin A (1 mol/L, c-Src family). The present findings show for the first time in intact resistance arteries that ERK1/2 activation is rapidly regulated by Ang II, is synergistic with pressure, and is involved in contraction. The ERK1/2 signaling pathway apparently includes upstream protein kinase C and c-Src. (Hypertension. 2000;36:617-621.)

Peroxisome Proliferator–Activated Receptor γ Regulates Angiotensin II–Stimulated Phosphatidylinositol 3-Kinase and Mitogen-Activated Protein Kinase in Blood Vessels In Vivo

“…Chronic Ang II infusion increased ERK 1/2 activity in the aorta but not in mesenteric arteries, which extends previous observations by Daigle et al 31 However, others found that ERK 1/2 activity increased after acute ex vivo stimulation of Ang II in pressurized mesenteric resistance vessels. 35 Basal ERK 1/2 activity was greater in mesenteric vessels compared with that of aorta, which may be an expression of the heterogeneity of the 2 vascular territories. It is noteworthy that the combined effects of BP elevation and Ang II increased ERK 1/2 activity in aorta to the level found in mesenteric arteries.…”

Involvement of Metalloproteinases 2/9 in Epidermal Growth Factor Receptor Transactivation in Pressure-Induced Myogenic Tone in Mouse Mesenteric Resistance Arteries

“…Frozen vessel segments were pulverized and resuspended in ice-cold lysis buffer. 4 All samples were immunoprecipitated with a anti-total EGFR antibody and then subjected to immunoblotting with an anti-phosphorylated EGFR antibody (1:1000, Cell Signaling Technology). Blots were stripped and reprobed with an anti-total EGFR antibody to verify gel loading.…”

“…Using mesenteric arteries, we reported a pressureinduced activation of ERK1/2 mitogen-activated protein (MAP) kinases in a tyrosine kinase-dependent manner, although the role of these signaling intermediates in pressureinduced MT was not investigated. 4,5 Other studies have shown that both rho kinase and protein kinase C (PKC) are involved in pressure-induced MT in mesenteric resistance vessels. 6 -8 However, it is unclear how mechanical stretch activates these intracellular signaling mechanisms and therefore MT development.…”

“…12,13 These contractile effects of Ang II are attributed largely to angiotensin II type I receptor (AT 1 -R) activation. 4 Multiple signal transduction cascades are stimulated by AT 1 -R in resistance vessels and in cultured aortic VSMCs, including extracellular recognition (ERK) MAP kinases, PKC, and tyrosine kinases such as PYK2. 14 -16 Recent studies have indicated that transactivation of the epidermal growth factor receptor (EGFR) may be an important upstream signaling intermediate that links AT 1 -R to these downstream signaling cascades.…”

Cyclooxygenase-2 Inhibitors Attenuate Angiotensin II–Induced Oxidative Stress, Hypertension, and Cardiac Hypertrophy in Rats

“…Lyses and Western blots were performed as described previously 14 with 20 g of proteins loaded on gels. For COX assay, rabbit COX-1 or COX-2 polyclonal antibody (USBiological) was used.…”