Human urotensin II in internal mammary and radial arteries of patients undergoing coronary surgery

Dexmedetomidine alleviates cardiomyocyte apoptosis and cardiac dysfunction may be associated with inhibition of RhoA/ROCK pathway in mice with myocardial infarction

The global incidence of myocardial infarction has been consistently high, and it is one of the main causes of poor cardiovascular prognosis. Dexmedetomidine (DEX) is a highly selective α2 receptor agonist. Recent studies have found that DEX has a protective effect on myocardial infarction, but its specific mechanism is still unclear. In this experiment, we permanently ligated the anterior descending branch of mice to explore the protective mechanism of DEX against myocardial infarction. Our study found that intraperitoneal injection of DEX for 7 days after myocardial infarction in mice can increase the reduction of ejection fraction (EF) and fractional shortening (FS) caused by myocardial infarction and significantly reduce the release of serum markers. The results of myocardial HE and Sirius red staining suggest that the changes in the myocardial structure of mice after using DEX are reduced. Immunohistochemistry shows that DEX reduces the expression of ROCK1 protein after myocardial infarction. TUNEL staining and the protein expression levels of cleaved caspase-3 and cleaved caspase-9 were used to detect cell apoptosis and results make clear that DEX can reduce the apoptosis caused by myocardial infarction. Western blot experiments showed that DEX can reduce the expression levels of ROCK1 and ROCK2 (Rho-kinase). At the same time, it was observed that DEX improved the Bcl-2/Bax ratio. The above results indicate that DEX reduces cardiomyocyte apoptosis and improves cardiac function likely through inhibiting the RhoA/ROCK signaling pathway. This study may provide new insights into the protective effect of DEX after myocardial infarction in mice.

Urotensin-#receptor antagonist SB-706375 protected isolated rat heart from ischaemia-reperfusion injury by attenuating myocardial necrosis via RhoA/ROCK/RIP3 signalling pathway

SB-706375 is a selective receptor antagonist of human urotensin-II (hU-II), which can block the aorta contraction induced by hU-II in rats. The effect of SB-706375 on myocardial ischaemia-reperfusion (I/R) injury is unclear. The major objective of this study was to investigate whether SB-706375 has a protective effect on myocardial I/R injury in rats and explore its possible mechanisms. Isolated hearts of Adult Sprague-Dawley were perfused in a Langendorff apparatus, and haemodynamic parameters, lactate dehydrogenase (LDH), creatine phosphokinase-MB (CK-MB), cardiac troponin I (cTnI), RhoA, and the protein expressions of U-II receptor (UTR), receptor-interacting protein 3 (RIP3), Rho-associated coiled-coil-containing protein kinase 1 (ROCK1) and Rho-associated coiled-coil-containing protein kinase 2 (ROCK2) were assessed. We found that SB-706375 (1 × 10-6 and 1 × 10-5 mol/L) significantly inhibited the changes of haemodynamic parameters and reduced LDH and CK-MB activities and also cTnI level in the coronary effluents in the heart subjected to myocardial I/R injury. Further experiments studies showed that SB-706375 obviously prevented myocardial I/R increased RhoA activity and UTR, RIP3, ROCK1, and ROCK2 protein expressions. ROCK inhibition abolished the improving effect of SB-706375 on myocardial I/R-induced haemodynamic change in the isolated perfused rat heart. These findings suggested that SB-706375 provides cardio-protection against I/R injury in isolated rats by blocking UTR-RhoA/ROCK-RIP3 pathway.

Arterial segments as microvascular interposition grafts in venous anastomosis in digital replantations

Introduction:

Microvascular anastomosis is a crucial procedure in replantation surgeries. Venous insufficiency is one of the most consistent cause of failure or re-exploration in these surgeries necessitating the use of venous grafts.

Materials and Methods:

We discuss our study of 9 such replantation surgeries executed in calendar year 2013-2014, including a double finger replantation done in the same patient having total amputation of 4 fingers of the same (right) hand, in which an arterial segment was used as a microvascular interposition graft for venous anastomosis. Out of these 9 surgeries, 3 were re-exploration procedures for venous compromise and 6 were successful primary replantations.

Results:

In all, 8 replants were successful and one failed due to arterial compromise.

Discussion:

In our experience and extensive review of the previously available literature, we would like to portray the advantages of arterial segments as microvascular grafts in replant surgeries. Specifically, in a crush amputation injury for which the use of a vascular interposition graft is being contemplated. If any other digit is also amputated and is unsuitable for replantation, it can act as a potential donor site to harvest the arterial segment. However, when dealing with single finger amputation, the surgeon must be confident about the single digital arterial anastomosis, before harvesting the second digital artery as a microvascular graft.

Conclusion:

In our study, we found the use of arterial grafts in microvascular anastomosis of veins advantageous, as arterial segments have better ability to resist spasm due to environmental changes, better pressure tolerance as compared to venous segments, and provide an appropriate calibre match and ease of harvest in the same operative field.

A new therapeutic approach to erectile dysfunction: urotensin-II receptor high affinity agonist ligands

Urotensin-II (U-II) is a cyclic peptide that acts through a G protein-coupled receptor (urotensin-II receptor [UTR]) mainly involved in cardiovascular function in humans. The urotensinergic system is also implicated in the urogenital tract. Indeed, U-II relaxes human corpus cavernosum strips and causes an increase in intracavernous pressure (ICP) in rats. In light of this, the U-II/UTR pathway can be considered a new target for the treatment of erectile dysfunction. On this hypothesis, herein we report on two new UTR high affinity-agonists, P5U (H-Asp-c[Pen-Phe-Trp-Lys-Tyr-Cys]-Val-OH) and UPG84(H-Asp-c[Pen-Phe-DTrp-Orn-(pNH₂) Phe-Cys]-Val-OH). The effects of P5U and UPG84 were each compared separately with U-II by monitoring the ICP in anesthetized rats. Intracavernous injection of U-II (0.03–1 nmol), P5U (0.03–1 nmol) or UPG84 (0.03–1 nmol) caused an increase in ICP. P5U, in particular, elicited a significant increase in ICP as compared to U-II. The observed effect by using P5U at a dose of 0.1 nmol per rat was comparable to the effect elicited by U-II at a dose of 0.3 nmol. Moreover, UPG84 at the lowest dose (0.03 nmol) showed an effect similar to the highest dose of U-II (1 nmol). Furthermore, UPG84 was found to be more effective than P5U. Indeed, while the lowest dose of P5U (0.03 nmol) did not affect the ICP, UPG84, at the same dose, induced a prominent penile erection in rat. These compounds did not modify the blood pressure, which indicates a good safety profile. In conclusion, UPG84 and P5U may open new perspectives for the management of erectile dysfunction.

Suxiao jiuxin pill induces potent relaxation and inhibition on contraction in human artery and the mechanism

Suxiao Jiuxin Pill, a compound Chinese traditional medicine with main components of tetramethylpyrazine and borneol, is widely used for antiangina treatment in China but its pharmacological effect on human blood vessels is unknown. We investigated the effect and possible mechanism of SJP in the human internal mammary artery (IMA, n = 78) taken from patients undergoing coronary surgery. SJP caused full relaxation in KCl- (99.4 ± 10.5%, n = 6) and U46619- (99.9 ± 5.6%, n = 6) contracted IMA. Pretreatment of IMA with plasma concentrations of SJP (1 mg/mL), calculated from the plasma concentration of its major component borneol, significantly depressed the maximal contraction to KCl (from 35.8 ± 6.0 mN to 12.6 ± 5.6 mN, P = 0.03) and U46619 (from 19.4 ± 2.9 mN to 5.7 ± 2.4 mN, P = 0.007) while SJP at 10 mg/mL abolished the subsequent contraction. Endothelium denudation and inhibition of eNOS significantly altered the SJP-induced relaxation without changes of eNOS expression. We conclude that SJP has a potent inhibitory effect on the vasoconstriction mediated by a variety of vasoconstrictors in human arteries. The vasorelaxation involves both endothelium-dependent and -independent mechanisms. Thus, the effect of SJP on human arteries demonstrated in this study may prove to be particularly important in vasorelaxing therapy in cardiovascular disease.

New molecule in the etiology of schizophrenia: urotensin II

AIMS

Urotensin II (U-II) is a cyclic peptide that was first isolated from the caudal neurosecretory system of goby fish. U-II receptors were detected in the vascular endothelium, brain and kidney cortex. Urotensin is by far the most powerful vasoconstrictor identified. U-II molecules were previously isolated from the brain of rats and were shown to have an impact on rat behavior. The aim of the present study was to measure the level of U-II molecule in schizophrenia patients and to investigate whether the U-II level is associated with the etiology of schizophrenia.

METHODS

Forty schizophrenia patients who were followed at Gaziantep University Faculty of Medicine Department of Psychiatry Psychotic Disorders Unit and 40 healthy volunteers were enrolled in this study. Blood samples were taken from the antecubital vein after 12-h fasting. U-II level was measured on ELISA.

RESULTS

The U-II level in schizophrenia patients was significantly higher than in the control group. U-II level was not different with regard to gender in either group. U-II level was not different between subgroups of schizophrenia. No significant correlation was found between U-II level, Positive and Negative Syndrome Scale and Clinical Global Impression-Severity scale scores.

CONCLUSION

U-II level was higher in schizophrenia patients, indicating that U-II level may be related to the etiology of the disease.

Urotensin II exerts antiapoptotic effect on NRK-52E cells through prostacyclin-mediated peroxisome proliferator-activated receptor alpha and Akt activation

Urotensin II (UII) is a cyclic vasoactive peptide which is mainly expressed in kidneys. Although elevated plasma UII levels are associated with renal impairment, the influence of UII on renal injury is unclear. In this study, we monitored the influence of UII on gentamicin-induced apoptosis in rat tubular cells (NRK-52E). We found that UII significantly reduced gentamicin-induced apoptosis and apoptotic signals. Blocking endogenous UII secretion caused cells to be more susceptible to gentamicin. In gentamicin-treated mice, UII also expressed protective effect on renal tubular cells. UII was also found to induce prostacyclin (PGI2) production, which caused peroxisomal proliferator-activated receptor α (PPARα) activation as revealed by both PGI2 synthase siRNA transfection and piroxicam treatment. Blockage of PPARα by siRNA transfection inhibited UII-induced Akt phosphorylation and the antiapoptotic effect of UII. Our results suggest that UII can protect renal tubular cells from gentamicin-induced apoptosis through PGI2-mediated PPARα and Akt activation.

Arterial grafts: clinical classification and pharmacological management

In comparison with standard saphenous vein grafts, use of the internal mammary artery (IMA) as a coronary artery bypass graft has achieved superior long-term results. This is related to the differences in the biological characteristics between the venous and arterial grafts. However, even arterial grafts are not uniform in their biological characteristics. The variation in the perioperative behavior of the grafts and in their long-term patency may be related to different characteristics. These factors should be taken into account in the use of arterial grafts, some of which are subjected to more active pharmacological intervention during and after the operation to obtain satisfactory results. To better understand the biological behavior of the grafts, their common features and their differences, a clinical classification may be useful for a practicing surgeon. Based on experimental studies of their vasoreactivity combined with anatomical, physiological and embryological considerations, we have proposed a functional classification for arterial grafts that may be useful clinically. Our classification suggests that there are three types of arterial grafts: Type I-somatic arteries; Type II-splanchnic arteries; and Type III-limb arteries. Type I arteries have enhanced endothelial function and release more nitric oxide and other relaxing factors. Type II arteries, such as the gastro-epiploic artery, and Type III arteries, such as the radial artery (RA), have higher pharmacological reactivity to vasoconstrictors. This classification explains why the IMA has the best long-term patency. Because Type II and III arteries are prone to spasms due to higher contractility, they require more active pharmacological interventions. Furthermore, the harvesting technique of the conduits, including the saphenous vein and IMA, are described and discussed in this article. Prevention of spasms using two cocktails of medications (verapamil + nitroglycerin and nicardipine + nitroglycerin) during harvesting of the conduits is described. These solutions have been demonstrated to be clinically effective.

Protective effect of urantide against ischemia-reperfusion injury via protein kinase C and phosphtidylinositol 3'-kinase - Akt pathway

Urantide is the most potent UT receptor antagonist compound found to date. Our previous studies have shown that it has cardioprotective effect against ischemia-reperfusion injury. However, it is unclear which signal transduction pathways are involved in the urantide-induced cardioprotective effect. This study was designed to investigate whether the effect of urantide on myocardial ischemia-reperfusion injury in rats via the protein kinase C (PKC) and phosphatidylinositol 3-kinase (PI3K)-Akt signaling pathway. The results showed that urantide at 10 and 30 µg/kg markedly inhibited the increases in serum creatine kinase fraction and lactate dehydrogenase activities and the level of cardiac troponin I, reduced the ratio of myocardial infarct size to area at risk. Urantide significantly decreased the histological damage to the myocardium and modified the ultrastructural damage in cardiac myocytes. In the presence of chelerythrine (an inhibitor of PKC, 1 mg/kg) or LY294002 (an inhibitor of PI3K-Akt, 0.3 mg/kg), the protective effect of urantide was almost completely abolished. Urantide (30 µg/kg) markedly enhanced the expression of p-Akt protein during myocardial ischemia-reperfusion injury, and this enhancement was significantly attenuated by LY294002. Therefore, our results demonstrate that urantide has a potent protective effect against myocardial ischemia-reperfusion injury in rats that may be involved with the PKC and PI3K-Akt signaling pathways.

The interaction between human urotensin II and vasodilator agents in human internal mammary artery with possible clinical implications

BACKGROUND

Graft spasm in the internal mammary artery (IMA) may occur after coronary artery bypass grafting (CABG). We investigated the effect of human urotensin II (hU-II), a cyclic peptide hormone present in human blood and tissues, and the effect of vasodilators on hU-II-mediated response in human IMA.

METHODS

Fresh IMA segments (n=114) taken from 50 patients undergoing CABG were studied in a myograph. The interaction between hU-II and various calcium antagonists or glyceryl trinitrate (GTN) was investigated in 2 ways: relaxing effect of vasodilators on the hU-II-induced precontraction and depressing effect of vasodilator agents on the contraction caused by hU-II (n=6 to 10 in each subgroup).

RESULTS

Human urotensin II caused contractile response in all human IMA. In potassium chloride-contraction, full (nifedipine: 99.1 %±2.7%) or nearly full (diltiazem: 93.5%±4.8%) relaxation with 30.9-fold higher potency to nifedipine than to diltiazem (EC50 [effective concentration causing 50% of maximal response] -8.24±0.21 vs -6.75±0.20 log M, p=0.0002) and in hU-II-contraction, nearly full relaxation (nifedipine: 90.6%±4.6%; diltiazem: 95.0%±1.7%) with 5.8-fold higher potency to nifedipine than to diltiazem (EC50 -7.55±0.26 vs -6.79±0.25 log M, p=0.03) were observed. The GTN caused nearly full relaxation (93.1%±4.8%) but GTN pretreatment had limited effect in prevention of the hU-II-induced contraction, whereas diltiazem and nifedipine reduced subsequent contraction to hU-II.

CONCLUSIONS

Human urotensin II is a potent vasoconstrictor in human IMA. Calcium antagonists and GTN relax the contraction caused by hU-II with different potencies. However, calcium antagonists are more effective than GTN in preventing the contraction induced by hU-II. These findings may have clinical implications in CABG.