8-11-14-eicosatrienoic-acid and Hypertension--Portal

In cirrhosis, 11,12-epoxyeicosatrienoic acid (EET) induces mesenteric arterial vasodilation, which contributes to the onset of portal hypertension. We evaluated the hemodynamic effects of in vivo inhibition of EET production in experimental cirrhosis. Sixteen control rats and 16 rats with carbon tetrachloride-induced cirrhosis were studied. Eight controls and eight rats with cirrhosis were treated with the specific epoxygenase inhibitor N-(methylsulfonyl)-2-(2-propynyloxy)-benzenehexanamide (MS-PPOH; 20 mg/kg/day) for 3 consecutive days. Portal blood flow and renal and splenic resistive indexes were calculated through echographic measurements, while portal and systemic pressures were measured through polyethylene-50 catheters. Small resistance mesenteric arteries were connected to a pressure servo controller in a video-monitored perfusion system, and concentration-response curves to phenylephrine and acetylcholine were evaluated. EET levels were measured in tissue homogenates of rat liver, kidney, and aorta, using an enzyme-linked immunosorbent assay. Urinary Na(+) excretion function was also evaluated. In rats with cirrhosis, treatment with MS-PPOH significantly reduced portal blood flow and portal pressure compared to vehicle (13.6 ± 5.7 versus 25.3 ± 7.1 mL/min/100 g body weight, P < 0.05; 9.6 ± 1.1 versus 12.2 ± 2.3 mm Hg, P < 0.05; respectively) without effects on systemic pressure. An increased response to acetylcholine of mesenteric arteries from rats with cirrhosis (50% effect concentration -7.083 ± 0.197 versus -6.517 ± 0.73 in control rats, P < 0.05) was reversed after inhibition of EET production (-6.388 ± 0.263, P < 0.05). In liver, kidney, and aorta from animals with cirrhosis, treatment with MS-PPOH reversed the increase in EET levels. In both controls and rats with cirrhosis, MS-PPOH increased urinary Na(+) excretion.. In rats with cirrhosis, in vivo inhibition of EET production normalizes the response of mesenteric arteries to vasodilators, with beneficial effects on portal hypertension. (Hepatology 2016;64:923-930).

Topics: 8,11,14-Eicosatrienoic Acid; Acetylcholine; Amides; Animals; Aorta; Drug Evaluation, Preclinical; Hypertension, Portal; Kidney; Liver; Liver Cirrhosis, Experimental; Male; Mesenteric Arteries; Rats, Wistar; Sodium; Splanchnic Circulation; Vascular Resistance

Cirrhotic portal hypertension is characterized by mesenteric arterial vasodilation and hyporeactivity to vasoconstrictors.. We evaluated the role of epoxyeicosatrienoic acid (EET) and of myoendothelial gap junctions (GJ) in the haemodynamic alterations of experimental cirrhosis.. Thirty-five control rats and 35 rats with carbon tetrachloride (CCl(4))-induced cirrhosis were studied. Small resistance mesenteric arteries (diameter <350 μm) were connected to a pressure servo controller in a video-monitored perfusion system. Concentration-response curves to acetylcholine (ACh) were evaluated in mesenteric arteries pre-incubated with indomethacin, N(G)-nitro-L-arginine-methyl-ester and 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one before and after the epoxygenase inhibitor miconazole or 18α-glycyrrhetinic acid (18α-GA) (GJ inhibitor). EC(50) was calculated. Concentration-response curves to 11,12-EET were also evaluated. mRNA and protein expression of connexins (Cxs) in the mesenteric arteries was evaluated by real-time PCR and immunohistochemistry.. The ACh response was increased in cirrhotic rats (EC(50): -6.55±0.10 vs. -6.01±0.10 log[M]; P<0.01) and was blunted by miconazole only in cirrhotic animals. 18α-GA blunted the response to ACh more in cirrhotic than that in control rats (P<0.05). Concentration-response curves to 11,12-EET showed an increased endothelium-dependent vasodilating response in cirrhotic rats (P<0.05); the BK(Ca) inhibitor Iberiotoxin (25 nM) blocked the response in normal rats but not in cirrhotic rats, while 18α-GA blunted the response in cirrhotic rats but not in control rats. An increased mRNA and protein expression of Cx40 and Cx43 in cirrhotic arteries was detected (P<0.05).. The increased nitric oxide/PGI(2)-independent vasodilation of mesenteric arterial circulation in cirrhosis is because of, at least in part, hyperreactivity to 11,12-EET through an increased expression of myoendothelial GJs.

Topics: 8,11,14-Eicosatrienoic Acid; Acetylcholine; Analysis of Variance; Animals; Carbon Tetrachloride; Connexins; Dose-Response Relationship, Drug; Endothelial Cells; Enzyme Inhibitors; Epoprostenol; Gap Junctions; Guanylate Cyclase; Hypertension, Portal; Immunohistochemistry; Liver Cirrhosis, Experimental; Logistic Models; Male; Mesenteric Arteries; Nitric Oxide; Nitric Oxide Synthase; Nonlinear Dynamics; Prostaglandin-Endoperoxide Synthases; Rats; Rats, Wistar; Receptors, Cytoplasmic and Nuclear; RNA, Messenger; Soluble Guanylyl Cyclase; Vasodilation; Vasodilator Agents

CYP450-dependent epoxyeicosatrienoic acids (EETs) are potent arterial vasodilators, while 20-hydroxyeicosatatraenoic acid (20-HETE) is a vasoconstrictor. We evaluated their role in the control of portal circulation in normal and cirrhotic (CCl(4) induced) isolated perfused rat liver. Phenylephrine (PE) and endothelin-1 (ET-1) increased portal perfusion pressure, as did arachidonic acid (AA), 20-HETE, and 11,12-EET. Inhibition of 20-HETE with 12,12-dibromododecenoic acid (DBDD) did not affect basal pressure nor the responses to PE, ET-1, or AA. However, inhibition of epoxygenase with miconazole caused a significant reduction in the response to ET-1 and to AA, without affecting neither basal pressure nor the response to PE. Hepatic vein EETs concentration increased in response to ET-1, and was increased in cirrhotic, compared to control, livers. 20HETE levels were non-measurable. Miconazole decreased portal perfusion pressure in cirrhotic livers. In conclusion, 20HETE and EETs increase portal resistance; EETs, but not 20-HETE, mediate in part the pressure response to ET-1 in the portal circulation and may be involved in pathophysiology of portal hypertension.

Topics: 8,11,14-Eicosatrienoic Acid; Animals; Arachidonic Acid; Carbon Tetrachloride; Cytochrome P-450 Enzyme System; Endothelin-1; Hepatic Veins; Hydroxyeicosatetraenoic Acids; Hypertension, Portal; Infusion Pumps; Liver; Liver Cirrhosis, Experimental; Male; Miconazole; Organ Culture Techniques; Oxidoreductases; Phenylephrine; Portal Pressure; Rats; Rats, Sprague-Dawley; Vascular Resistance; Vasoconstriction; Vasodilation