title: Endothelin-1, but not angiotensin II, induces afferent arteriolar myosin diphosphorylation as a potential contributor to prolonged vasoconstriction.
abstract: Bolus administration of endothelin-1 elicits long-lasting renal afferent arteriolar vasoconstriction, in contrast to transient constriction induced by angiotensin II. Vasoconstriction is generally evoked by myosin regulatory light chain (LC20) phosphorylation at Ser19 by myosin light chain kinase (MLCK), which is enhanced by Rho-associated kinase (ROCK)-mediated inhibition of myosin light chain phosphatase (MLCP). LC20 can be diphosphorylated at Ser19 and Thr18, resulting in reduced rates of dephosphorylation and relaxation. Here we tested whether LC20 diphosphorylation contributes to sustained endothelin-1 but not transient angiotensin II-induced vasoconstriction. Endothelin-1 treatment of isolated arterioles elicited a concentration- and time-dependent increase in LC20 diphosphorylation at Thr18 and Ser19. Inhibition of MLCK or ROCK reduced endothelin-1-evoked LC20 mono- and diphosphorylation. Pretreatment with an ETB but not an ETA receptor antagonist abolished LC20 diphosphorylation, and an ETB receptor agonist induced LC20 diphosphorylation. In contrast, angiotensin II caused phosphorylation exclusively at Ser19. Thus, endothelin-1 and angiotensin II induce afferent arteriolar constriction via LC20 phosphorylation at Ser19 due to calcium activation of MLCK and ROCK-mediated inhibition of MLCP. Endothelin-1, but not angiotensin II, induces phosphorylation of LC20 at Thr18. This could contribute to the prolonged vasoconstrictor response to endothelin-1.
authors.affiliation: 1] Smooth Muscle Research Group and Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada [2] Smooth Muscle Research Group and Department of Physiology and Pharmacology, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Kosuke
authors.initials: K
authors.lastname: Takeya
authors.affiliation: Smooth Muscle Research Group and Department of Physiology and Pharmacology, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Xuemei
authors.initials: X
authors.lastname: Wang
authors.affiliation: 1] Smooth Muscle Research Group and Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada [2] Smooth Muscle Research Group and Department of Physiology and Pharmacology, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Iris
authors.initials: I
authors.lastname: Kathol
authors.affiliation: Smooth Muscle Research Group and Department of Physiology and Pharmacology, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Kathy
authors.initials: K
authors.lastname: Loutzenhiser
authors.affiliation: Smooth Muscle Research Group and Department of Physiology and Pharmacology, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Rodger
authors.initials: R
authors.lastname: Loutzenhiser
authors.affiliation: Smooth Muscle Research Group and Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Walsh
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology / Q000502:physiology*; D000818:Animals; D001160:Arterioles / Q000187:drug effects / Q000502:physiology*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects; D004110:Diltiazem / Q000494:pharmacology; D065130:Endothelin A Receptor Antagonists / Q000494:pharmacology; D019332:Endothelin-1 / Q000494:pharmacology / Q000502:physiology*; D008955:Models, Cardiovascular; D018994:Myosin Light Chains / Q000737:chemistry / Q000378:metabolism*; D009219:Myosin-Light-Chain Kinase / Q000037:antagonists & inhibitors / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D044023:Receptor, Endothelin B / Q000819:agonists; D015398:Signal Transduction / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D002121:Calcium Channel Blockers; D065130:Endothelin A Receptor Antagonists; D019332:Endothelin-1; D018994:Myosin Light Chains; D044023:Receptor, Endothelin B; D000804:Angiotensin II; D054460:rho-Associated Kinases; D009219:Myosin-Light-Chain Kinase; D004110:Diltiazem