Hydrogen sulfide (H2S) is synthesized in the body from L-cysteine by several enzymes including cystathionine-gamma-lyase (CSE). To date, there is little information about the potential role of H2S in inflammation. We have now investigated the part played by H2S in endotoxin-induced inflammation in the mouse. E. coli lipopolysaccharide (LPS) administration produced a dose (10 and 20 mg/kg ip)- and time (6 and 24 h)-dependent increase in plasma H2S concentration. LPS (10 mg/kg ip, 6 h) increased plasma H2S concentration from 34.1 +/- 0.7 microM to 40.9 +/- 0.6 microM (n=6, P<0.05) while H2S formation from added L-cysteine was increased in both liver and kidney. CSE gene expression was also increased in both liver (94.2+/-2.7%, n=6, P<0.05) and kidney (77.5+/-3.2%, n=6, P<0.05). LPS injection also elevated lung (148.2+/-2.6%, n=6, P<0.05) and kidney (78.8+/-8.2%, n=6, P<0.05) myeloperoxidase (MPO, a marker of tissue neutrophil infiltration) activity alongside histological evidence of lung, liver, and kidney tissue inflammatory damage. Plasma nitrate/nitrite (NOx) concentration was additionally elevated in a time- and dose-dependent manner in LPS-injected animals. To examine directly the possible proinflammatory effect of H2S, mice were administered sodium hydrosulfide (H2S donor drug, 14 micromol/kg ip) that resulted in marked histological signs of lung inflammation, increased lung and liver MPO activity, and raised plasma TNF-alpha concentration (4.6+/-1.4 ng/ml, n=6). In contrast, DL-propargylglycine (CSE inhibitor, 50 mg/kg ip), exhibited marked anti-inflammatory activity as evidenced by reduced lung and liver MPO activity, and ameliorated lung and liver tissue damage. In separate experiments, we also detected significantly higher (150.5+/-43.7 microM c.f. 43.8+/-5.1 microM, n=5, P<0.05) plasma H2S levels in humans with septic shock. These findings suggest that H2S exhibits proinflammatory activity in endotoxic shock and suggest a new approach to the development of novel drugs for this condition.

Moore PK. Hydrogen sulfide and its possible roles in myocardial ischemia in experimental rats. J Appl Physiol 102: [261][262][263][264][265][266][267][268] 2007. First published October 12, 2006; doi:10.1152/japplphysiol.00096.2006.-The role of hydrogen sulfide (H 2S) in myocardial infarction (MI) has not been previously studied. We therefore investigated the effect of H 2S in a rat model of MI in vivo. Animals were randomly divided into three groups (n ϭ 80) and received either vehicle, 14 mol/kg of sodium hydrosulfide (NaHS), or 50 mg/kg propargylglycine (PAG) everyday for 1 wk before surgery, and the treatment was continued for a further 2 days after MI when the animals were killed. The mortality was 35% in vehicletreated, 40% in PAG-treated, and 27.5% in NaHS-treated (P Ͻ 0.05 vs. vehicle) groups. Infarct size was 52.9 Ϯ 3.5% in vehicle-treated, 62.9 Ϯ 7.6% in PAG-treated, and 43.4 Ϯ 2.8% in NaHS-treated (P Ͻ 0.05 vs. vehicle) groups. Plasma H 2S concentration was significantly increased after MI (59.2 Ϯ 7.16 M) compared with the baseline concentration (i.e., 38.2 Ϯ 2.07 M before MI; P Ͻ 0.05). Elevated plasma H 2S after MI was abolished by treatment of animals with PAG (39.2 Ϯ 5.02 M). We further showed for the first time cystathioninegamma-lyase protein localization in the myocardium of the infarct area by using immunohistochemical staining. In the hypoxic vascular smooth muscle cells, we found that cell death was increased under the stimuli of hypoxia but that the increased cell death was attenuated by the pretreatment of NaHS (71 Ϯ 1.2% cell viability in hypoxic vehicle vs. 95 Ϯ 2.3% in nonhypoxic control; P Ͻ 0.05). In conclusion, endogenous H 2 S was cardioprotective in the rat model of MI. PAG reduced endogenous H 2S production after MI by inhibiting cystathionine-gamma-lyase. The results suggest that H 2S might provide a novel approach to the treatment of MI.cardioprotection; gasomediator; cardiac protection; ischemic animal model FOR MANY YEARS, HYDROGEN SULFIDE (H 2 S) has been considered solely as a broad-spectrum environmental toxicant with effects on many major organ systems, including the lung, brain, and kidney (2, 11). However, the possible physiological role(s) of H 2 S in the cardiovascular system have only recently come to light. It has been suggested that H 2 S interferes with cardiovascular function as a result of anoxia rather than a direct action on cardiac myocytes or vascular smooth muscle cells (13). However, this possibility now appears less certain in light of more recent research. The localization of H 2 S-generating enzymes and the detection of biologically significant levels of H 2 S in plasma and tissue homogenate from animals have recently been reported (20). Endogenous H 2 S is formed locally by the activity of two pyridoxal-5Ј-phosphate-dependent enzymes, namely cystathionine ␤-synthase and cystathionine ␥-lyase (CSE), each of which utilize L-cysteine as substrate (17). Although cystathionine ␤-synthase does not appear to play a major role in generating H 2 S in cardiovasc...

Cytochrome P450 (CYP) epoxygenases CYP2C8 and CYP2J2 generate epoxyeicosatrienoic acids (EETs) from arachidonic acid. Mice with expression of CYP2J2 in cardiomyocytes (αMHC-CYP2J2 Tr) or treated with synthetic EETs have increased functional recovery after ischemia/reperfusion (I/R); however, no studies have examined the role of cardiomyocyte- vs. endothelial-derived EETs or compared the effects of different CYP epoxygenase isoforms in the ischemic heart. We generated transgenic mice with increased endothelial EET biosynthesis (Tie2-CYP2C8 Tr and Tie2-CYP2J2 Tr) or EET hydrolysis (Tie2-sEH Tr). Compared to wild-type (WT), αMHC-CYP2J2 Tr hearts showed increased recovery of left ventricular developed pressure (LVDP) and decreased infarct size after I/R. In contrast, LVDP recovery and infarct size were unchanged in Tie2-CYP2J2 Tr and Tie2-sEH Tr hearts. Surprisingly, compared to WT, Tie2-CYP2C8 Tr hearts had significantly reduced LVDP recovery (from 21 to 14%) and increased infarct size after I/R (from 51 to 61%). Tie2-CYP2C8 Tr hearts also exhibited increased reactive oxygen species (ROS) generation, dihydroxyoctadecenoic acid (DiHOME) formation, and coronary resistance after I/R. ROS scavengers and CYP2C8 inhibition reversed the detrimental effects of CYP2C8 expression in Tie2-CYP2C8 Tr hearts. Treatment of WT hearts with 250 nM 9,10-DiHOME decreased LVDP recovery compared to vehicle (16 vs. 31%, respectively) and increased coronary resistance after I/R. These data demonstrate that increased ROS generation and enhanced DiHOME synthesis by endothelial CYP2C8 impair functional recovery and mask the beneficial effects of increased EET production following I/R.

Abstract. The purpose of the current study is to evaluate the cardioprotective effects of purified Salvia miltiorrhiza extract (PSME) on myocardial ischemia / reperfusion injury in isolated rat hearts. Hearts were excised and perfused at constant flow (7 -9 ml ⋅ min −1 ) via the aorta. Non-recirculating perfusion with Krebs-Henseleit (KH) solution was maintained at 37°C and continuously gassed with 95% O 2 and 5% CO 2 . KH solution with or without PSME (100 mg per liter solution) was used after 30-min zero-flow ischemia for the PSME and control group, respectively. Left ventricular (LV) developed pressure; its derivatives, diastolic pressure, and so on were continuously recorded via a pressure transducer attached to a polyvinylchloride balloon that was placed in the left ventricle through an incision in the left atrium. PSME treated hearts showed significant postischemic contractile function recovery (developed pressure recovered to 44.2 ± 4.9% versus 17.1 ± 5.7%, P<0.05; maximum contraction recovered to 57.2 ± 5.9% versus 15.1 ± 6.3%, P<0.001; maximum relaxation restored to 69.3 ± 7.3% versus 15.4 ± 6.3%, P<0.001 in the PSME and control group, respectively). Significant elevation in end-diastolic pressure, which indicated LV stiffening in PSME hearts might have resulted from the excess high dose of PSME used. Further study will be conducted on the potential therapeutic value with lower dose of PSME on prevention of ischemic heart disease.