Role of ADP-ribose in 11,12-EET-induced activation of K(Ca) channels in coronary arterial smooth muscle cells.
We recently reported that cADP-ribose (cADPR) and ADP-ribose (ADPR) play an important role in the regulation of the Ca(2+)-activated K(+) (K(Ca)) 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 K(Ca) 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*(-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 K(Ca) channel activity by 5.6-fold. The NAD glycohydrolase inhibitor cibacron blue 3GA (3GA, 100 microM) significantly attenuated 11,12-EET-induced increase in the K(Ca) channel activity in CASMCs. However, 3GA had no effect on the K(Ca) 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 microM) 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 K(Ca) channels in CASMCs and consequently results in vasodilation of coronary artery.
Li
Pin-Lan
PL
Department of Pharmacology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA. pli@post.its.mcw.edu
Zhang
David X
DX
Ge
Zhi-Dong
ZD
Campbell
William B
WB
D015126:8,11,14-Eicosatrienoic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology*; D000246:Adenosine Diphosphate Ribose / Q000378:metabolism*; D000818:Animals; D016718:Arachidonic Acid / Q000494:pharmacology; D001160:Arterioles / Q000187:drug effects / Q000502:physiology; D002417:Cattle; D003331:Coronary Vessels / Q000187:drug effects / Q000502:physiology*; D006893:Hydroxyeicosatetraenoic Acids / Q000494:pharmacology; D066298:In Vitro Techniques; D007700:Kinetics; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology*; D009599:Nitroprusside / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D024681:Potassium Channels, Calcium-Activated / Q000187:drug effects / Q000502:physiology*; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology
D006893:Hydroxyeicosatetraenoic Acids; D024681:Potassium Channels, Calcium-Activated; D009599:Nitroprusside; D000246:Adenosine Diphosphate Ribose; D016718:Arachidonic Acid; C046783:11,12-epoxy-5,8,14-eicosatrienoic acid; C055987:20-hydroxy-5,8,11,14-eicosatetraenoic acid; D015126:8,11,14-Eicosatrienoic Acid