Early propranolol treatment ameliorates endothelial dysfunction in experimental septic lung

BACKGROUND

Recent reports have indicated an improved prognosis in sepsis with β-blocker agents; however, the underlying action mechanism is still under debate.

OBJECTIVES

The aim of this study was to investigate the potential effect of propranolol on endothelial dysfunction in septic rats.

MATERIAL AND METHODS

The cecal ligation and puncture model (CLP) was used to generate sepsis. Adult male Wistar-Albino rats were divided into 4 groups: group 1 was a sham group, group 2 received sterile saline, group 3 received 10 mg/kg of propranolol 3 days before the intervention, and group 4 received 10 mg/kg of propranolol 30 min after CLP. Six rats from each group were sacrificed 24 h postoperatively. The remaining rats were followed for survival. We have also evaluated the effects on systemic inflammation, coagulation and the lung tissue with immunohistochemical and electron microscopic evaluation.

RESULTS

Serum tumor necrosis factor alpha (TNF-α) and plasminogen activator inhibitor-1 (PAI-1) levels, as well as tissue TNF-α scores were elevated in septic rats. Electron microscopic examination of the lung tissue showed endothelial dysfunction in the sepsis group. Pretreatment significantly improved survival. Moreover, pre-treatment altered serum vascular endothelial growth factor receptor-1 (VEGFR-1) levels and post-treatment reduced serum PAI-1 and VEGFR-1 levels. In both the preand post-treatment groups, electron microscopic examination revealed improvement of the destroyed lung endothelium and showed only mild alterations in the cytoplasmic organelles, especially in the mitochondria of the endothelial cells.

CONCLUSIONS

These results suggest that the improved outcome with β-blockers in sepsis may be due to the ameliorated endothelial dysfunction. Further studies focusing on the potential effect of β-blockers on the endothelium may lead to a better understanding of sepsis.

Effect of silymarin on bladder overactivity in cyclophosphamide-induced cystitis rat model

The purpose of this study was to investigate the effects of silymarin, a phytotherapeutic agent, on bladder overactivity in a cyclophosphamide (CYP)-induced cystitis rat model. Female Wistar Albino rats received a single intraperitoneal injection of CYP (150 mg/kg) or saline and after 72 h, bladder function was evaluated by in vitro preparations of whole bladders and cystometry with continuous saline infusion under urethane anesthesia. Silymarin or a vehicle was orally given for 7 days in rats. CYP was injected on the 5th day of silymarin or vehicle treatment and then the animals were killed on the 8th day. CYP-treatment dramatically potentiated the basal spontaneous contractions of isolated whole bladders compared to control rats. In anesthetized rats, during continuous infusion cystometry, intercontraction interval (ICI) was significantly shorter, but bladder voiding pressure was not significantly changed in CYP-injected rats compared to control rats. In the CYP-injected group, silymarin treatment significantly decreased the amplitude, frequency (contractions/min) and area under the curve of spontaneous contractions, but failed to change carbachol-induced contraction in isolated whole bladder. Also, silymarin treatment significantly increased the ICI in comparison to the vehicle treatment. In the saline-injected group, no significant changes in the bladder function were observed between the silymarin and vehicle-treated groups. Histopathological examination showed that CYP-induced bladder inflammation tended to be lower in the silymarin+CYP-treated group. In conclusion, the oral administration of silymarin suppressed CYP-induced bladder overactivity. Silymarin may be considered as an attractive treatment for CYP-induced bladder overactivity.

Differential effect of neocuproine, a copper(I) chelator, on contractile activity in isolated ovariectomized non-pregnant rat, pregnant rat and pregnant human uterus

The study was conducted to examine effects of a selective copper(I) chelator, neocuproine on the spontaneous or oxytocin-induced contractions in isolated ovariectomized non-pregnant rat, pregnant rat and pregnant human uterus. Uterus activity was evaluated in tissues obtained from bilaterally ovariectomized non-pregnant rats on the 21st day of the operation (n = 24), pregnant rats on the 19-21st day of gestation (n = 24) and women undergoing caesarean section at 38-42 weeks of pregnancy (n = 15). Neocuproine (100 microM) significantly suppressed the amplitude and frequency of the spontaneous contractions in the ovariectomized non-pregnant rat uterus while this agent facilitated the frequency of the spontaneous or oxytocin-induced contractions in the pregnant rat and human uterus without altering the amplitude of these contractions. At high concentration of 200 microM, neocuproine could enhance the amplitude of the contractions in the pregnant uterus. These effects were blocked by a purinergic receptor antagonist, suramin (100 microM) and did not occur following the administration of neocuproine-copper(I) complex or copper(II) chelator cuprizone. alpha, beta-methylene ATP increased the amplitude and frequency of contractions in the pregnant uterus, but not affected the contractions in the ovariectomized non-pregnant rat uterus, and neocuproine potentiated this facilitation effect. However, the suppressive effect of neocuproine on the ovariectomized non-pregnant rat uterus increased in the presence of alpha,beta-methylene ATP. Beta-adrenoceptor blocker, propranolol or nitric oxide synthase inhibitor, L-nitroarginine did not affect the responses to neocuproine. These findings suggest that neocuproine can affect the uterus contractile activity by modulation purinergic excitatory responses and that copper(I)-sensitive mechanisms may play a role in this effect.