Abstract 650: Mechanism Underlying The Increased Contractile Sensitivity In Serum-free Organ-cultured Rat Mesenteric Artery
Background: Organ culture of blood vessels in a serum-free condition is a better way to maintain differentiated cell function. However some functional changes may occur from freshly isolated blood vessel (Fresh). The removal of proteins (enzymes and regulatory proteins) is essential for the control of cell growth and metabolism. Failure to remove an essential protein or lack of degradation of a short-lived regulatory protein may alter cell function in a major way. We thus hypothesized that the ubiquitin proteasome system may be a candidate which causes functional changes. The aim of the present study was to investigate the effects of an inhibitor of ubiquitin proteasome on increased contractile sensitivity in serum-free organ-cultured rat mesenteric arteries.
Methods and results: Rat isolated mesenteric arteries with endothelium were cultured for 5 days without (0% serum) or with an ubiquitin proteasome inhibitor, Bortezomib (Bort; 10 nM). In 0% serum, sensitivity to KCl (5.4-75.4 mM) and phenylephrine (0.01-100 uM) significantly increased from Fresh (KCl: EC50 (mM) for 0% serum and Fresh was 18.3 and 40.3, respectively, p<0.01) (phenylephrine: pD2 for 0% serum and Fresh was 6.58 and 5.07, respectively, p<0.01), while maximal contraction significantly decreased. In Bort, the increased sensitivity to KCl and phenylephrine was significantly normalized (EC50 for Bort was 24.9 (mM) and pD2 for Bort was 3.99, respectively, p<0.01), while maximal contraction did not change from 0% serum. A rho-associated kinase inhibitor, Y27632-induced relaxation in Bort significantly decreased from 0% serum, while relaxation induced by aβ-adrenergic receptor agonist, isoproterenol, a phosphodiesterase 3 inhibitor, cilostazol, a protein kinase C inhibitor, Go6983 and a phospholipase C inhibitor, U73122 did not change between 0% serum and Bort.
Conclusion: These data suggest that ubiquitin proteasome system increases contractile sensitivity via a rho-associated kinase in serum-free organ cultured mesenteric artery. Elucidation of the mechanism might contribute to provide mechanistic insights into the role of ubiquitin proteasome system on pathogenesis of hypertension.
Author Disclosures: T. Morita: None. M. Okada: None. H. Yamawaki: None.
- © 2014 by American Heart Association, Inc.