MAPK and PKC activity are not required for H(2)O(2)-induced arterial muscle contraction.
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.
Pelaez
N J
NJ
Department of Physiology and Biophysics, Indiana University School of Medicine, Indianapolis, Indiana 46202-5120, USA.
Osterhaus
S L
SL
Mak
A S
AS
Zhao
Y
Y
Davis
H W
HW
Packer
C S
CS
D000818:Animals; D015153:Blotting, Western; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000378:metabolism* / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000201:enzymology* / Q000502:physiology; D010766:Phosphorylation / Q000187:drug effects; D011189:Potassium Chloride / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D011651:Pulmonary Artery / Q000187:drug effects / Q000201:enzymology / Q000502:physiology; D013552:Swine; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*
D004791:Enzyme Inhibitors; D005419:Flavonoids; D011189:Potassium Chloride; D006861:Hydrogen Peroxide; D017346:Protein Serine-Threonine Kinases; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; D013755:Tetradecanoylphorbol Acetate; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one