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Nitric oxide‐dependent β 2 ‐adrenergic dilatation of rat aorta is mediated through activation of both protein kinase A and Akt
Author(s) -
Ferro Albert,
Coash Marcy,
Yamamoto Takahiro,
Rob Jubli,
Ji Yong,
Queen Lindsay
Publication year - 2004
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1038/sj.bjp.0705933
Subject(s) - protein kinase b , nitric oxide , protein kinase a , adrenergic , cgmp dependent protein kinase , chemistry , aorta , kinase , medicine , nitric oxide synthase , endocrinology , phosphorylation , microbiology and biotechnology , mitogen activated protein kinase kinase , biochemistry , biology , receptor
Vasorelaxation to β 2 ‐adrenoceptor stimulation occurs through both endothelium‐dependent and endothelium‐independent mechanisms, and the former is mediated through Ca 2+ ‐independent activation of endothelial‐type nitric oxide synthase (NOS‐3). Since Ca 2+ ‐independent NOS‐3 activation may occur through its serine phosphorylation via protein kinase A (PKA) or Akt, we determined the PKA and Akt dependency of β 2 ‐adrenergic relaxation of rat aorta. Rat aortic rings were pre‐incubated with the PKA inhibitor H‐89 (10 −7 M ), the phosphatidylinositol 3‐kinase (PI3K) inhibitor wortmannin (5 × 10 −7 M ), Akt inhibitor (10 −5 M ), or vehicle, in the absence or presence of the NOS inhibitor N G ‐nitro‐ L ‐arginine methyl ester ( L ‐NAME, 10 −4 M ). Rings were then contracted with phenylephrine (10 −7 M ), and concentration–relaxation responses determined to the β 2 ‐adrenoceptor agonist albuterol. Rings exhibited a concentration‐dependent relaxation to albuterol: p EC 50 6.9±0.2, E max 88.2±4.0%. L ‐NAME attenuated E max to 60.2±3.5% ( P <0.001). In the presence of L ‐NAME, wortmannin or Akt inhibitor did not influence albuterol responses, whereas H‐89 reduced E max further, to 27.5±2.2% ( P <0.001). In the absence of L ‐NAME, E max to albuterol was reduced by H‐89, wortmannin or Akt inhibitor, to 56.2±2.2, 56.0±1.6 and 55.4±1.8%, respectively ( P <0.001 for each); the combinations H‐89 plus wortmannin or H‐89 plus Akt inhibitor reduced E max further still. Western blotting of NOS‐3 immunoprecipitates from rat aortas confirmed that albuterol increased serine phosphorylation of NOS‐3, and this increase was attenuated by H‐89 or Akt inhibitor. Our results indicate that β 2 ‐adrenoceptor stimulation relaxes rat aorta through both NO‐dependent and independent mechanisms. The latter is predominantly PKA‐mediated, whereas the former occurs through both PKA and PI3K/Akt activation.British Journal of Pharmacology (2004) 143 , 397–403. doi: 10.1038/sj.bjp.0705933