MAPK and PKC activity are not required for H(2)O(2)-induced arterial muscle contraction

• Published in: American journal of physiology. Heart and circulatory physiology 2000-09, Vol.279 (3), p.H1194
• Main Authors: Pelaez, N J, Osterhaus, S L, Mak, A S, Zhao, Y, Davis, H W, Packer, C S
• Format: Article
• Language: English
• Subjects: Animals; Blotting, Western; Electrophoresis, Polyacrylamide Gel; Enzyme Inhibitors - pharmacology; Flavonoids - pharmacology; Hydrogen Peroxide - metabolism; Hydrogen Peroxide - pharmacology; In Vitro Techniques; Male; Mitogen-Activated Protein Kinases - metabolism; Muscle, Smooth, Vascular - drug effects; Muscle, Smooth, Vascular - enzymology; Muscle, Smooth, Vascular - physiology; Phosphorylation - drug effects; Potassium Chloride - pharmacology; Protein Kinase C - metabolism; Protein-Serine-Threonine Kinases - antagonists & inhibitors; Pulmonary Artery - drug effects; Pulmonary Artery - enzymology; Pulmonary Artery - physiology; Swine; Tetradecanoylphorbol Acetate - pharmacology; Vasoconstriction - drug effects; Vasoconstriction - physiology
• ISSN: 0363-6135

H(2)O(2)-induced pulmonary arterial smooth muscle (PASM) contractions are independent of Ca(2+) and myosin light chain phosphorylation. The purpose of this study was to determine whether mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase (ERK) 1 and ERK2, or protein kinase C (PKC) activation is required for H(2)O(2)-induced contraction. Porcine PASM strips were stimulated with 1 mM H(2)O(2), 120 mM KCl, or 10 microM phorbol myristic acetate and freeze clamped at various times during the contractions. Changes in relative amounts of tyrosine/threonine phosphorylated MAPK compared with total MAPK were measured. MAPK tyrosine phosphorylation levels increased in correlation with tension development. However, 50 microM PD-98059, a MAPK/ERK kinase-MAPK kinase blocker, reduced MAPK phosphorylation below resting levels, even though the magnitude of the isometric tension development was unaltered. Freeze-clamped PASM strips were placed in a PKC activity assay buffer containing (32)P and CaCl(2) to measure the total myelin basic protein phosphorylation. The data show that: 1) the time courses of PKC activity and force produced in response to H(2)O(2) do not correlate, and 2) MAPK activation may be a concurrent event with, or a consequence of, tension development in response to a variety of agonists but is not responsible for contractions to H(2)O(2), high K(+), or phorbol esters.