Effects of magnesium sulfate on heart rate, blood pressure variability and baroreflex sensitivity in preeclamptic rats treated with L-NAME

Acetylcholinesterase inhibition with Pyridostigmine attenuates hypertension and neuroinflammation in the paraventricular nucleus in rat model for Preeclampsia

Preeclampsia (PE) is characterized by hypertension, autonomic imbalance and inflammation. The subfornical organ (SFO) reportedly relays peripheral inflammatory mediator's signals to the paraventricular nucleus (PVN), a brain autonomic center shown to mediate hypertension in hypertensive rat but not yet in PE rat models. Additionally, we previously showed that Pyridostigmine (PYR), an acetylcholinesterase inhibitor, attenuated placental inflammation and hypertension in PE models. In this study, we investigated the effect of PYR on the activities of these brain regions in PE model. PYR (20 mg/kg/day) was administered to reduced uterine perfusion pressure (RUPP) Sprague-Dawley rat from gestational day (GD) 14 to GD19. On GD19, the mean arterial pressure (MAP) was recorded and samples were collected for analysis. RUPP rats exhibited increased MAP (P = 0.0025), elevated circulating tumor necrosis factor-α (TNF-α, P = 0.0075), reduced baroreflex sensitivity (BRS), increased neuroinflammatory markers including TNF-α, interleukin-1β (IL-1β), microglial activation (P = 0.0039), oxidative stress and neuronal excitation within the PVN and the SFO. Changes in MAP, in molecular and cellular expression induced by RUPP intervention were improved by PYR. The ability of PYR to attenuate TNF-α mediated central effect was evaluated in TNF-α-infused pregnant rats. TNF-α infusion-promoted neuroinflammation in the PVN and SFO in dams was abolished by PYR. Collectively, our data suggest that PYR improves PE-like symptoms in rat by dampening placental ischemia and TNF-α-promoted inflammation and pro-hypertensive activity in the PVN. This broadens the therapeutical potential of PYR in PE.

Renoprotective and therapeutic effects of newly water, ethanol, and butanol ginseng fractions in hypertensive and chronic kidney disease with L-NAME

The present study investigated the protective and treatment effects of different ginseng fractions against L-NAME-induced renal toxicity in rats. The data obtained demonstrated that L-NAME significantly increased creatinine, urea, KIM-1, and lipocalin-2 levels in serum; and also increased renal MDA and eNOS levels compared with the control group. Three bioactive fractions were newly extracted from ginseng, analyzed by GC-MS analysis, and were examined for antimicrobial, prebiotic, and histological activities. All ginseng fractions improved such histological changes, as reflected by significant reductions in creatinine, urea, KIM-1, and LCN-2 levels in serum, and renal MDA and eNOS contents in tissue homogenate. The water ginseng fraction (WGF) has the highest prebiotic index of 4.7 toward Lactobacillus reuteri, and can improve the renal functions more than butanol ginseng fraction (BGF) and ethanol ginseng fraction (EGF). These three ginseng fractions significantly reversed L-NAME-induced depletion in the TNF-α gene expression level. Interestingly, WGF was able to improve the renal functions more than BGF and EGF. L-NAME led to alterations in the histological structure and functions of renal tissue of rats and ginseng supplementation could offer greater protection against these changes. Moreover, the WGF exhibited superior renoprotection properties when compared with the other two fractions: BGF and EGF, and the reference drug losartan.

Establishing low-density lipoprotein apheresis tolerability in patients with prior anaphylactoid reactions to lipoprotein apheresis using magnesium sulfate

BACKGROUND

Lipoprotein apheresis (LA) tolerability is a key factor for the utilization of this therapy. Common reactions to LA are hypotension and nausea. Serious reactions include severe hypotension and anaphylactoid reactions (0.13%-1.3% and 0.2%-0.4%, respectively). The bradykinin response drives these reactions and can worsen with the use of angiotensin-converting-enzyme inhibitors. Efforts to mitigate these reactions are necessary for the tolerability of LA with a dextran sulfate-adsorption (DSA) system.

MATERIALS AND METHODS

In an effort to increase apheresis tolerability, seven patients at The University of Kansas, Department of Clinical Pharmacology, who had prior anaphylactoid reactions (defined as general cutaneous flushing, nausea/vomiting, tongue swelling, lightheadedness, and hypotension) to the DSA despite pharmacologic intervention, were treated with pre-LA intravenous magnesium adapted from a protocol developed by co-author Eliaz. This protocol consists of 1.5 g of magnesium sulfate administered over 45 minutes. All seven patients were treated with intravenous magnesium sulfate immediately before LA.

RESULTS

No episodes of anaphylactoid reactions during LA have been reported to date.

CONCLUSIONS

Magnesium infusion before DSA can be utilized to establish tolerability in patients with prior anaphylactoid reactions to LA. Proposed mechanisms include temporary stabilization of the negative-positive interactions of the dextran sulfate filter leading to a reduction of circulating bradykinin, reduction of nitric oxide, and reduction of the sympathetic response to LA.

Changes in Maternal Heart Rate Variability in Response to the Administration of Routine Obstetric Medication in Hospitalized Patients: Study Protocol for a Cohort Study (MAMA-Heart Study)

Pregnancy is a period of continuous change in the maternal cardiovascular system, partly mediated by the autonomic nervous system. Insufficient autonomic adaptation to increasing gestation is associated with pregnancy complications, such as hypertensive disorders of pregnancy and preterm birth (both major causes of perinatal morbidity and mortality). Consequently, maternal heart rate variability (mHRV), which is a proxy measure for autonomic activity, is increasingly assessed in these cohorts to investigate the pathophysiology of their complications. A better pathophysiological understanding could facilitate the early detection of these complications, which remains challenging. However, such studies (typically performed in pregnancies leading to hospitalization) have generated conflicting findings. A probable reason for these conflicting findings is that these study cohorts were likely administered routine obstetric medications during the study period of which the effects on mHRV are largely unknown. Subsequently, we design a longitudinal, observational study to quantifying the effect of these medications-particularly corticosteroids, which are known to affect fetal HRV-on mHRV to improve the interpretation of past and future studies. We will enroll 61 women admitted to a tertiary obstetric unit with an indication to receive corticosteroids antenatally. Participants' mHRV will be continuously acquired throughout their hospitalization with wrist-worn photoplethysmography to facilitate a within-patient comparison of the effect of corticosteroids on mHRV.

Radio-Telemetric Assessment of Cardiac Variables and Locomotion With Experimentally Induced Hypermagnesemia in Horses Using Chronically Implanted Catheters

The objective of this study was to characterize the pharmacokinetics and pharmacodynamics of intravenous administration of magnesium sulfate to horses using a novel radio-telemetry system for physiologic signal capture. Five Horses were surgically implanted with a radio-telemetric carotid catheter. Implants were paired with a non-invasive telemetric unit which acquired a six lead ECG and 3-axis acceleration to assess activity acquired wirelessly in real-time for future analysis. Horses were exposed to a new stall environment before (baseline) and after 60 mg/kg (30 mL) of magnesium sulfate (MgSO₄), or the same volume of 0.9% saline, administered intravenously in a blinded, random crossover design. Blood for pharmacokinetics, telemetric data, and body temperature were recorded serially for 24 h. Data were analyzed across time and between treatments. Significance was set at P < 0.05. Ionized magnesium concentration (Mg²⁺) increased and the Ca²⁺ to Mg²⁺ ratio decreased and persisted for 5 h after MgSO₄ administration. Heart rate (HR) increased and mean arterial blood pressure (MAP) decreased for at least 6 h. Electrocardiogram (ECG) intervals (RR) decreased and (PR and QTc) increased in duration compared to controls indicating an increase in heart rate, and slower myocardial conduction in the MgSO₄ group. Acceleration in all planes was less in the MgSO₄ group compared to controls indicating decreased locomotion. This novel method permitted collection of physiologic signals without interference by handlers or animal restraint. An intravenous bolus of MgSO₄ produced cardiac variable changes associated with the reduction of locomotion in these horses, and in a direction that may be causal. Locomotion was decreased when horses were first introduced into a new environment which reflects the calming effect desired in sport horses. Telemetric monitoring can be used as a model to elucidate the behavior and physiologic effects of other drugs. The administration of MgSO₄ may be detected for regulatory purposes with the monitoring of Mg²⁺ and Ca²⁺ concentrations and their ratio.

Vitexin ameliorates preeclampsia phenotypes by inhibiting TFPI-2 and HIF-1α/VEGF in a l-NAME induced rat model

Preeclampsia (PE) is a leading cause of maternal and perinatal morbidity and mortality with few safe, effective, and minimally invasive therapeutics. Inflammation, oxidative stress, and angiogenic imbalance have been reported to contribute to PE pathogenesis. Vitexin (VI) possesses various pharmacological activities including the potent regulation of the above biological processes in different conditions. This study aims to investigate whether VI has therapeutic potential to PE and the underlying mechanisms. Sprague-Dawley pregnant rats pretreated with or without VI were fed with l-NAME-containing water to induce experimental PE. Results showed that VI decreased high systolic blood pressure and urinary protein in PE rats time- and dose-dependently. Meanwhile, VI of higher dosage (45, 60 mg/kg) corrected abnormal pregnancy outcomes, including low pup weight and low pups/placenta ratio. In addition, VI of high dosage (60 mg/kg) decreased sFlt-1, increased PlGF and alleviated oxidative stress both in blood and placental samples compared with nontreated PE group. Furthermore, VI alleviated placental TFPI-2, HIF 1α, and VEGF in PE rats. In short, the present study suggests that the inhibition of placental TFPI-2 and HIF-1α/VEGF might be one of the potential mechanisms underlying the protective effects of VI to experimental PE induced by l-NAME.

Vitamin D restores angiogenic balance and decreases tumor necrosis factor-α in a rat model of pre-eclampsia

AIM

Deficiency of vitamin D is correlated with pre-eclampsia (PE), a hypertensive disorder of pregnancy, and is characterized by angiogenic imbalance and inflammation. The aim of this study was to investigate whether vitamin D supplementation can restore the angiogenic balance and ameliorate inflammation in a rat model of PE.

METHODS

PE was induced using l-nitroarginine methylester. Normal pregnant and PE-induced rats were supplemented with vitamin D on gestation days 14-19.

RESULTS

Blood pressure was significantly increased in PE-induced rats compared with normal pregnant rats (P < 0.05), and vitamin D supplementation ameliorated this difference. In addition, rats from the PE group had lower vascular endothelial growth factor (VEGF; P < 0.01), and higher plasma-soluble FMS-like tyrosine kinase-1 (sFlt-1) and tumor necrosis factor-α (TNF-α; P < 0.01 for both) compared with the normal pregnant group. The vitamin D treatment group had significantly increased VEGF, and reduced sFlt-1 and TNF-α compared with the untreated PE group. Moreover, vitamin D supplementation was able to reduce the oxidative stress by lowering the plasma oxidative stress marker malondialdehyde.

CONCLUSION

Vitamin D supplementation plays an important role in restoring angiogenic balance and reducing inflammation in pregnancy-induced hypertension.

Beneficial Effects of Magnesium Treatment on Heart Rate Variability and Cardiac Ventricular Function in Diabetic Rats

BACKGROUND

Diabetes mellitus induces life-threatening cardiovascular complications such as cardiac autonomic neuropathy and ventricular dysfunction and is associated with hypomagnesemia. In this study, we investigated the short-term effects of magnesium (Mg²⁺) treatment on streptozotocin (STZ)-induced diabetic cardiac complications.

METHODS

Adult Wistar rats were treated once with STZ (50 mg/kg, intraperitoneally [ip]) or vehicle (citrate) and then daily for 7 days with MgSO₄ (270 mg/kg, ip) or saline. On the eighth day, in vivo tail-pulse plethysmography was recorded for heart rate variability (HRV) analysis, and ex vivo Langendorff-based left ventricular (LV) pressure-volume parameters were measured using an intraventricular balloon. Measurements of plasma lipid and Mg²⁺ levels as well as blood glucose and cardiac tissue Mg²⁺ levels were also performed.

RESULTS

Treatment with Mg²⁺ prevented diabetes-induced alterations in the standard deviation of the averages of normal-to-normal (NN) intervals (SDANN), root mean square differences of successive NN intervals (RMSSD), heart rate, and low-frequency (LF) power-high-frequency (HF) power ratio. In addition, Mg²⁺ restored orthostatic stress-induced changes in SDANN, RMSSD, and LF-HF ratio in diabetic rats. In isolated hearts, Mg²⁺ reversed the diabetes-induced decrease in LV end-diastolic elastance and the right shift of end-diastolic equilibrium volume intercept, without altering LV-developed pressure or end-systolic elastance. However, Mg²⁺ did not prevent the elevation in blood glucose, total cholesterol, and triglycerides or the decrease in high-density lipoprotein cholesterol in diabetes. Plasma- or cardiac tissue Mg²⁺ was not different among the treatment groups.

CONCLUSION

These results suggest that Mg²⁺ treatment may attenuate diabetes-induced reduction in HRV and improve LV diastolic distensibility, without preventing hyperglycemia and dyslipidemia. Thus, Mg²⁺ may have a modulatory role in the early stages of diabetic cardiovascular complications.

A combined supplementation of omega-3 fatty acids and micronutrients (folic acid, vitamin B12) reduces oxidative stress markers in a rat model of pregnancy induced hypertension

Objectives

Our earlier studies have highlighted that an altered one carbon metabolism (vitamin B₁₂, folic acid, and docosahexaenoic acid) is associated with preeclampsia. Preeclampsia is also known to be associated with oxidative stress and inflammation. The current study examines whether maternal folic acid, vitamin B₁₂ and omega-3 fatty acid supplementation given either individually or in combination can ameliorate the oxidative stress markers in a rat model of pregnancy induced hypertension (PIH).

Materials and Methods

Pregnant Wistar rats were assigned to control and five treatment groups: PIH; PIH + vitamin B₁₂; PIH + folic acid; PIH + Omega-3 fatty acids and PIH + combined micronutrient supplementation (vitamin B₁₂ + folic acid + omega-3 fatty acids). L-Nitroarginine methylester (L-NAME; 50 mg/kg body weight/day) was used to induce hypertension during pregnancy. Blood Pressure (BP) was recorded during pregnancy and dams were dissected at d20 of gestation.

Results

Animals from the PIH group demonstrated higher (p<0.01 for both) systolic and diastolic BP; lower (p<0.01) pup weight; higher dam plasma homocysteine (p<0.05) and dam and offspring malondialdehyde (MDA) (p<0.01), lower (p<0.05) placental and offspring liver DHA and higher (p<0.01) tumor necrosis factor–alpha (TNF–ά) levels as compared to control. Individual micronutrient supplementation did not offer much benefit. In contrast, combined supplementation lowered systolic BP, homocysteine, MDA and placental TNF-ά levels in dams and liver MDA and protein carbonyl in the offspring as compared to PIH group.

Conclusion

Key constituents of one carbon cycle (folic acid, vitamin B₁₂ and DHA) may play a role in reducing oxidative stress and inflammation in preeclampsia.

Fatty acid oxidation changes and the correlation with oxidative stress in different preeclampsia-like mouse models

Background

Long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) expression is decreased in placenta of some cases of preeclampsia (PE) which may result in free fatty acid (FFA) increased. High FFA level will induce oxidative stress, so abnormal long-chain fatty acid-oxidation may participate in the pathogenesis of PE through oxidative stress pathway.

Methods

PE-like groups were ApoC3 transgenic mice with abnormal fatty acid metabolism, classical PE-like models with injection of Nw-nitro-L-arginine-methyl ester (L-NA) or lipopolysaccharide (LPS) and the antiphospholipid syndrome (APS) mouse model with β2GPI injection (ApoC3+NS, ApoC3+L-NA, L-NA, LPS and β2GPI groups). The control group was wild-type mice with normal saline injection. Except for β2GPI mice, the other mice were subdivided into pre-implantation (Pre) and mid-pregnancy (Mid) subgroups by injection time.

Results

All PE-like groups showed hypertension and proteinuria except ApoC3+NS mice only showed hypertension. Serum FFA levels increased significantly except in LPS group compared to controls (P<0.05). LCHAD mRNA and protein expression in the liver and placenta was significantly higher for ApoC3+NS, ApoC3+L-NA and β2GPI mice and lower for L-NA mice than controls (P<0.05) but did not differ between LPS mice and controls. P47phox mRNA and protein expression in the liver significantly increased in all PE-like groups except LPS group, while P47phox expression in the placenta only significantly increased in L-NA and β2GPI groups.

Conclusions

Abnormal long-chain fatty acid-oxidation may play a different role in different PE-like models and in some cases participate in the pathogenesis of PE through oxidative stress pathway.