Role of ADP-ribose in 11,12-EET-induced activation of K_Cachannels in coronary arterial smooth muscle cells

Abstract

We recently reported that cADP-ribose (cADPR) and ADP-ribose (ADPR) play an important role in the regulation of the Ca2+-activated K+ (KCa) channel activity in coronary arterial smooth muscle cells (CASMCs). The present study determined whether these novel signaling nucleotides participate in 11,12-epoxyeicosatrienoic acid (11,12-EET)-induced activation of the KCa channels in CASMCs. HPLC analysis has shown that 11,12-EET increased the production of ADPR but not the formation of cADPR. The increase in ADPR production was due to activation of NAD glycohydrolase as measured by a conversion rate of NAD into ADPR. The maximal conversion rate of NAD into ADPR in coronary homogenate was increased from 2.5 ± 0.2 to 3.4 ± 0.3 nmol · min−1 · mg protein−1 by 11,12-EET. The regioisomers of 8,9-EET, 11,12-EET, and 14,15-EET also significantly increased ADPR production from NAD. Western blot analysis and immunoprecipitation demonstrated the presence of NAD glycohydrolase, which mediated 11,12-EET-activated production of ADPR. In cell-attached patches, 11,12-EET (100 nM) increases KCa channel activity by 5.6-fold. The NAD glycohydrolase inhibitor cibacron blue 3GA (3GA, 100 μM) significantly attenuated 11,12-EET-induced increase in the KCa channel activity in CASMCs. However, 3GA had no effect on the KCa channels activity in inside-out patches. 11,12-EET produced a concentration-dependent relaxation of precontracted coronary arteries. This 11,12-EET-induced vasodilation was substantially attenuated by 3GA (30 μM) with maximal inhibition of 57%. These results indicate that 11,12-EET stimulates the production of ADPR and that intracellular ADPR is an important signaling molecule mediating 11,12-EET-induced activation of the KCa channels in CASMCs and consequently results in vasodilation of coronary artery.

Epoxide hydrolase and epoxygenase metabolites as therapeutic targets for renal diseases

“…11,12-EET and 14,15-EET have been demonstrated to activate K Ca channels in cerebral and coronary vascular smooth muscle cells (4,12,39,59,107). ADP ribosylation is one intracellular mechanism that has been demonstrated to activate K Ca channels in coronary arteries (59). More recently, epoxides have also been shown to hyperpolarize platelets by activating K Ca channels and 11,12-EET was the most potent of the regioisomers (58).…”

“…The ability of EETs to activate K Ca channels is not limited to the renal vasculature or vascular smooth muscle cells (2,4,12,39,59,107). 11,12-EET and 14,15-EET have been demonstrated to activate K Ca channels in cerebral and coronary vascular smooth muscle cells (4,12,39,59,107). ADP ribosylation is one intracellular mechanism that has been demonstrated to activate K Ca channels in coronary arteries (59).…”

Regulation of TRPM2 channels in neutrophil granulocytes by ADP-ribose: a promising pharmacological target

“…As a preliminary test to which extent ADPR-Ca 2+ -dependent Ca 2+ influx contributes to the total fMLP-induced [Ca 2+ ] i signal, we performed experiments with cibacron blue (Kim et al 1993;Li et al 2002a), also named 3GA. 3GA is an inhibitor of NAD glycohydrolases that convert NAD to ADPR (Fig.…”

Human CYP4F3s are the main catalysts in the oxidation of fatty acid epoxides

“…EETs are products of cytochrome P450 epoxygenase, mainly CYP2C8 in human liver (20,21); they are endowed with important vasodilatating and antiinflammatory properties and serve as components of cell signaling cascades (22)(23)(24)(25)(26). EETs were shown to accumulate in alcoholic liver disease in rat (27) and increased in the rat kidney during liver cirrhosis (28).…”