The effects of transient systemic hypotension on renal oxidative status, morphology and plasma nitric oxide levels in pregnant rats

Trace elements cause oxidative damage in the brain of rats with induced hypotension

Hypertension causes neuronal damage and apoptosis in the brain. Diazoxide is a drug used in the treatment of hypertension however, its effect on 5-hydroxyindole acetic acid (5-HIAA) and dopamine amines in adult animal models remains unclear. The purpose of this study was to determine the effect of oligoelements on 5-HIAA and dopamine in the brain of adult rats treated with diazoxide METHODS: Male Fisher rats (weight 250g) were treated as follows: Group I, NaCl 0.9% (control); group II, tracefusin® (1.5mL/rat); group III, diazoxide (20mg/rat) and group IV, tracefusin® (1.5mL/rat)+diazoxide (20mg/rat). All doses were intraperitoneally administered on daily basis for four consecutive days. After the last administration, the brain of the animals was obtained and dissected in cortex, hemispheres (striatum) and cerebellum/medulla oblongata to measure the levels of 5-HIAA, dopamine, lipid peroxidation and total ATPase activity through validated methods.

RESULTS

Dopamine and 5-HIAA levels decreased significantly in the group that received trace elements and diazoxide in the hemisphere regions, while in cerebellum/medulla oblongata, dopamine levels increased significantly in the groups that received diazoxide alone in. Lipid peroxidation in all brain regions increased significantly in the groups that received trace elements and diazoxide. ATPase dependent of calcium and magnesium decreased in the groups that received diazoxide alone or combined with trace elements in cerebellum/medulla oblongata regions.

CONCLUSION

The present results suggest that the use of trace elements and diazoxide alters metabolism of dopamine and 5-HIAA amines. Free radicals may be involved in this effect.

Inhibition of inducible nitric oxide synthase ameliorates myocardial ischemia/reperfusion injury - induced acute renal injury

OBJECTIVES

Acute kidney injury occurs frequently in patients subsequent to coronary artery revascularization or myocardial ischemia and reperfusion (MIR). Hypotension and excessive nitric oxide (NO) production through inducible nitric oxide synthase (iNOS) were implicated in renal injury. On the other hand, NO may have a protective role during early reperfusion. In this study, we aim to compare protective effectiveness of 1,400W, a highly selective iNOS inhibitor, and L-NG-nitroarginine methyl ester (L-NAME), a non-specific nitric oxide synthase (NOS) inhibitor, against MIR-induced hemodynamic stabilization and kidney injury.

METHODS

Male Sprague-Dawley rats were evenly divided in four groups including sham-operated, MIR, and groups pretreated with 1,400W (20 mg/kg, intraperitoneally, [ip]) or L-NAME (30 mg/kg, ip) 15 minutes before MIR. Ischemia was conducted by occluding the left coronary artery for 30 minutes, followed by 120 minutes of reperfusion. We determined the measured aortic pressure (MAP) and assessed kidney injury through serum levels of blood urea nitrogen (BUN), methylguanidine (MG), malondialdehyde (MDA) and NO at different phases during the study.

RESULTS

MAP, decreased during myocardial ischemia, increased during early reperfusion; however, that was abolished with L-NAME pretreatment, and the increase was moderate with 1,400W pretreatment. Serum MDA, MG and BUN levels, although relatively unaltered during ischemia, significantly increased after 120 minutes of reperfusion. Treatment with 1,400W reduced post-reperfusion MDA and MG levels (P < .05), but the improvement was not significant with L-NAME.

CONCLUSIONS

1,400W was effective in reducing MIR-induced hemodynamic instability and kidney injury, in contrast to no apparent protection with L-NAME administration.

Effect of transient maternal hypotension on apoptotic cell death in foetal rat brain

BACKGROUND

Intrauterine perfusion insufficiency induced by transient maternal hypotension has been reported to be associated with foetal brain malformations. However, the effects of maternal hypotension on apoptotic processes in the foetal brain have not been investigated experimentally during the intrauterine period.

AIMS

The aim of this study was to investigate the effects of transient maternal hypotension on apoptotic cell death in the intrauterine foetal brain.

STUDY DESIGN

Animal experimentation.

METHODS

Three-month-old female Wistar albino rats were allocated into four groups (n=5 each). The impact of hypoxic/ischemic injury induced by transient maternal hypotension on the 15th day of pregnancy (late gestation) in rats was investigated at 48 (H17 group) or 96 hours (H19 group) after the insult. Control groups underwent the same procedure except for induction of hypotension (C17 and H17 groups). Brain sections of one randomly selected foetus from each pregnant rat were histopathologically evaluated for hypoxic/ischemic injury in the metencephalon, diencephalon, and telencephalon by terminal transferase-mediated dUTP nick end labelling and active cysteine-dependent aspartate-directed protease-3 (caspase-3) positivity for cell death.

RESULTS

The number of terminal transferase-mediated dUTP nick end labelling (+) cells in all the areas examined was comparable in both hypotension and control groups. The H17 group had active caspase-3 (+) cells in the metencephalon and telencephalon, sparing diencephalon, whereas the C19 and H19 groups had active caspase-3 (+) cells in all three regions. The number of active caspase-3 (+) cells in the telencephalon in the H19 group was higher compared with the metencephalon and diencephalon and compared with H17 group (p<0.05).

CONCLUSION

Our results suggest that prenatal hypoxic/ischemic injury triggers apoptotic mechanisms. Therefore, blockade of apoptotic pathways, considering the time pattern of the insult, may constitute a potential neuroprotective approach for the detrimental effects of prenatal hypoperfusion.

Normal urine output after elective caesarean section: an observational study

BACKGROUND

When monitoring postoperative urine output there is no guidance specific to obstetrics. Factors such as peri-operative oxytocin infusions add further complexity. Our aim was to determine a normal range for urine output after elective caesarean section under neuraxial anaesthesia.

METHODS

Sixty women were recruited and for 24h from the time of urethral catheterisation, we recorded urine output and fluid input. We also measured intra-operative blood loss, use of prophylactic oxytocin infusion and markers of renal function. Data were compared with Mann-Whitney U-tests or paired t tests.

RESULTS

Oxytocin infusions were used in 45 women (75%). Median (95% CI) urine output in the first 6h was 0.8 (0.4-1.9) mL kg(-1)h(-1) in women receiving oxytocin compared to 1.4 (0.7-2.2)mL kg(-1)h(-1) in those who did not (P=0.02). Urine output for all women at 12 and 18 h was 2.0 (0.7-5.7) and 1.9 (0.5-4.5)mL kg(-1)h(-1). Blood loss was 0.4 (0.2-0.8)L in women with oxytocin infusions and 0.3 (0.1-0.4)L in those without (P=0.003). Mean (SD) pre- and postoperative urine osmolality was 622.5 (185.7) and 293.0 (135.1) mosm/kg, respectively (P<0.0001).

CONCLUSIONS

Urine output varied widely between subjects, especially after the first 6h and was further reduced by the use of oxytocin infusion. This may have been a direct effect or related to increased blood loss in this group. Oxytocin use should be accounted for when setting a minimum postoperative urine output. We also found high pre-operative urine osmolalities suggesting significant dehydration.