title: Angiotensin II modulates mouse skeletal muscle resting conductance to chloride and potassium ions and calcium homeostasis via the AT1 receptor and NADPH oxidase.
abstract: Angiotensin II (ANG II) plays a role in muscle wasting and remodeling; however, little evidence shows its direct effects on specific muscle functions. We presently investigated the acute in vitro effects of ANG II on resting ionic conductance and calcium homeostasis of mouse extensor digitorum longus (EDL) muscle fibers, based on previous findings that in vivo inhibition of ANG II counteracts the impairment of macroscopic ClC-1 chloride channel conductance (gCl) in the mdx mouse model of muscular dystrophy. By means of intracellular microelectrode recordings we found that ANG II reduced gCl in the nanomolar range and in a concentration-dependent manner (EC50 = 0.06 μM) meanwhile increasing potassium conductance (gK). Both effects were inhibited by the ANG II receptors type 1 (AT1)-receptor antagonist losartan and the protein kinase C inhibitor chelerythrine; no antagonism was observed with the AT2 antagonist PD123,319. The scavenger of reactive oxygen species (ROS) N-acetyl cysteine and the NADPH-oxidase (NOX) inhibitor apocynin also antagonized ANG II effects on resting ionic conductances; the ANG II-dependent gK increase was blocked by iberiotoxin, an inhibitor of calcium-activated potassium channels. ANG II also lowered the threshold for myofiber and muscle contraction. Both ANG II and the AT1 agonist L162,313 increased the intracellular calcium transients, measured by fura-2, with a two-step pattern. These latter effects were not observed in the presence of losartan and of the phospholipase C inhibitor U73122 and the in absence of extracellular calcium, disclosing a Gq-mediated calcium entry mechanism. The data show for the first time that the AT1-mediated ANG II pathway, also involving NOX and ROS, directly modulates ion channels and calcium homeostasis in adult myofibers.
authors: Unit of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari "A. Moro," Bari, Italy; and.
authors: Anna
authors: A
authors: Cozzoli
authors: Unit of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari "A. Moro," Bari, Italy; and.
authors: Antonella
authors: A
authors: Liantonio
authors: Unit of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari "A. Moro," Bari, Italy; and.
authors: Elena
authors: E
authors: Conte
authors: Unit of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari "A. Moro," Bari, Italy; and.
authors: Maria
authors: M
authors: Cannone
authors: Unit of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari "A. Moro," Bari, Italy; and.
authors: Ada Maria
authors: AM
authors: Massari
authors: Department of Biomedical Sciences and Human Oncology, University of Bari "A. Moro," Bari, Italy.
authors: Arcangela
authors: A
authors: Giustino
authors: Unit of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari "A. Moro," Bari, Italy; and.
authors: Antonia
authors: A
authors: Scaramuzzi
authors: Unit of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari "A. Moro," Bari, Italy; and.
authors: Sabata
authors: S
authors: Pierno
authors: Unit of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari "A. Moro," Bari, Italy; and.
authors: Paola
authors: P
authors: Mantuano
authors: Unit of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari "A. Moro," Bari, Italy; and.
authors: Roberta Francesca
authors: RF
authors: Capogrosso
authors: Unit of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari "A. Moro," Bari, Italy; and.
authors: Giulia Maria
authors: GM
authors: Camerino
authors: Unit of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari "A. Moro," Bari, Italy; and annamaria.deluca@uniba.it.
authors: Annamaria
authors: A
authors: De Luca
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology*; D047228:Angiotensin II Type 1 Receptor Blockers / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D002712:Chlorides / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D056966:Excitation Contraction Coupling / Q000187:drug effects; D016166:Free Radical Scavengers / Q000494:pharmacology; D006706:Homeostasis; D008297:Male; D008564:Membrane Potentials; D008810:Mice, Inbred C57BL; D018485:Muscle Fibers, Skeletal / Q000187:drug effects* / Q000201:enzymology; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects; D011188:Potassium / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D044140:Receptor, Angiotensin, Type 1 / Q000819:agonists* / Q000378:metabolism; D013997:Time Factors
chemical_list: D047228:Angiotensin II Type 1 Receptor Blockers; D002712:Chlorides; D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; D017382:Reactive Oxygen Species; D044140:Receptor, Angiotensin, Type 1; D000804:Angiotensin II; D019255:NADPH Oxidases; D011188:Potassium; D002118:Calcium
keywords: AT1 receptor; NADPH oxidase; angiotensin II; chloride channel conductance; protein kinase C