Role of Tyrosine Phosphorylation in U46619-induced Vasoconstriction of Pulmonary Vasculature and Its Modulation by Genistein, Daidzein, and Equol

Abstract

We compared the effects of genistein with its structural derivatives daidzein and equol on excitation of pulmonary artery and vein. The concentration of genistein necessary to inhibit contractions evoked by U46619 (1nM-100 microM) ranged from 10 to 100 microM. Genistein (55 microM) reduced KCl-responses by approximately 50% and essentially abolished those evoked by U46619. Daidzein was much less effective against either agonist, and equol was ineffective against U46619. A23187-evoked contractions were markedly reduced by all 3 isoflavones, but caffeine-evoked contractions were not. Using the Western blot technique, we found many proteins were tyrosine phosphorylated within 30 seconds after stimulation with U46619, reaching a peak at 120 seconds and then falling at 300 seconds. One band at 110 kD was increased nearly 300% above baseline, while 3 others ranging from 60 to 80 kD were more than doubled in intensity. Genistein had little effect on baseline levels of phosphorylation but largely prevented the U46619-induced change; daidzein was much less effective in this respect, and equol did not significantly affect this phosphorylation. We conclude that these isoflavones provide powerful tools in the study of excitation-contraction coupling of pulmonary vasculature and that inhibition of tyrosine kinase activity may be useful clinically against pulmonary hypertension.

Functional expression of the TMEM16 family of calcium-activated chloride channels in airway smooth muscle

“…C: benzbromarone pretreatment prior to a substance P contractile challenge also results in significant attenuation in airway smooth muscle force generation compared with vehicle control. ***P Ͻ 0.001, n ϭ 8. rents by acetylcholine, histamine, substance P, and caffeine in previous studies in airway smooth muscle cells (13,14,16,17,20,21,29). Schroeder et al (26), using an expression system of Xenopus laevis for CaCC mRNA, generated CaCC currents that became less dependent upon voltage and showed little rectification at high intracellular calcium levels.…”

Effects of genistein and daidzein on erythrocyte membrane fluidity: an electron paramagnetic resonance study

“…It should be mentioned that both genistein and daidzein block the membrane ion channels in vitro, without involvement of tyrosine kinase inhibition (Paillart et al 1997). However, genistein does operate as a specific inhibitor of tyrosine kinases and could be of use in vasoconstriction-caused pulmonary hypertension, while daidzein is much less effective in this respect (Liu et al 2007). Obviously, the fine structural difference between these isoflavones determines their protein-phospholipid interactions, reflecting a number of molecular mechanisms in cell membranes.…”

Discovery of a Novel, Orally Active Himbacine-Based Thrombin Receptor Antagonist (SCH 530348) with Potent Antiplatelet Activity

“…The effect of 4 on aggregation responses to thrombin (10 nM), haTRAP (15 µM), ADP (20 µM), and collagen (5 µM) in human platelet-rich plasma (PRP) was evaluated in a comparative experiment. The compound showed potent inhibition of thrombin-induced platelet aggregation with an IC 50 of 47 nM and haTRAP-induced platelet aggregation with an IC 50 of 25 nM, whereas it showed no inhibition of platelet aggregation induced by other agonists such as ADP, collagen, a standard thromboxane mimetic 9,11-dideoxy-11α,9α-epoxymethanoprostaglandin F2α (U46619), and a PAR-4 agonist peptide.…”