Effects of intravenous magnesium infusion on in vivo release of acetylcholine and catecholamine in rat adrenal medulla

The Association Between Dietary Magnesium Intake with Chronic Obstructive Pulmonary Disease and Lung Function in US Population: a Cross-sectional Study

Chronic obstructive pulmonary disease (COPD) is now considered among the top three contributors to mortality globally. There is limited understanding surrounding the contribution of magnesium to the progression of COPD. This survey aims to evaluate the connection between dietary magnesium intake and both lung function and COPD prevalence among the US population. The research comprised 4865 participants in the National Health and Nutrition Examination Survey (NHANES) program conducted from 2007 to 2012. To evaluate the association between dietary magnesium intake and lung function as well as COPD, the study conducted multiple regression analyses, stratified analyses, and smoothed curves. In this study, we explored the relationship between higher magnesium intake and higher FEV1 [β = 0.21 (95% CI 0.12, 0.30)] and FVC [β = 0.25 (95% CI 0.14, 0.36)] after accounting for all potential confounding factors. We demonstrated a relationship between increased magnesium intake and reduced odds of developing COPD [OR = 0.9993 (95% CI 0.9987, 1.0000)]. The results of stratified analyses further indicated that the relationship between magnesium intake and the risk of COPD is more pronounced in the 40-60 age group and males. The study demonstrated positive associations between the intake of dietary magnesium and both FEV1 and FVC. Additionally, an adverse relationship between magnesium intake and the prevalence of COPD was also observed, suggesting that supplementation with magnesium may be a practical approach to preventing and managing COPD.

Unrecognised pheochromocytoma in pregnancy discovered through metoclopramide-triggered hypertensive emergency

PURPOSE

Pheochromocytoma, a catecholamine-secreting tumour leading to neurological and cardiovascular life-threatening conditions through hypertension crisis, occurs in 0.1-0.5% of hypertensive patients, but it is extremely rare in pregnancy (0.0018-0.006%). Some classes of drugs, even commonly used in pregnancy, can trigger catecholamine secretion, precipitating the clinical situation.

MATERIALS AND METHODS AND RESULTS

We report a 33-year-old woman, gravida 2 para 1, with previous mild hypertension, was admitted to the emergency room, at 28 2/7 weeks of gestation due to headache, tachycardia and severe arterial hypertension (220/120 mm Hg) triggered by the antiemetic metoclopramide used for a week because of nausea. In the emergency room, a paradoxical rise in blood pressure followed intravenous labetalol infusion was observed. Both metoclopramide and labetalol-triggered hypertensive crisis raised the suspicion of an undiagnosed pheochromocytoma. Diagnostic work-up showed elevated normetanephrine urinary excretion ​​and a right adrenal pheochromocytoma by abdominal magnetic resonance imaging. Oral alpha-1 and beta-1-adrenergic antagonist and calcium-channel blocker were started. At 33-weeks of gestation, she underwent a caesarean section giving birth to a female child. Seven weeks later she underwent a video-laparoscopic right adrenalectomy which normalised her blood pressure.

CONCLUSIONS

Both metoclopramide, a selective dopamine type-2 receptor antagonist and partial agonist of 5-hydroxytryptamine 4 receptor, and labetalol, a non-selective β-adrenoreceptor-blocker with weak α1-adrenergic antagonism, exacerbated an acute hypertensive crisis revealing an unrecognised pheochromocytoma in a pregnant patient. Careful attention to potential drug-triggered catecholamine crises and especially early recognition of pheochromocytomas, are mandatory in hypertensive pregnant women. A missed or delayed diagnosis could result in catastrophic results affecting foetal and maternal outcomes.

Effect of magnesium sulfate on baroreflex during acute hypoxemia in chronically instrumented fetal sheep

AIM

To investigate the effects of magnesium sulfate on fetal baroreflex in normoxemia or acute fetal hypoxemia.

METHODS

Fetal baroreflex response was elicited using phenylephrine (30 μg) in saline and magnesium sulfate in 8 chronically treated and instrumented fetal sheep. Hypoxemia was induced using nitrogen gas inflow for 30 min. Baroreflex, calculated as the ratio of the fetal heart rate change to the mean arterial pressure, was monitored after magnesium sulfate administration and in rapid and nonrapid eye movement (NREM) sleep states. Baroreflex was assessed in response to hypoxemia in control groups in both the rapid and NREM sleep states.

RESULTS

Baroreflex was not significantly affected by saline, magnesium sulfate and rapid or NREM sleep states in normoxemic sheep. Hypoxemia increased the baroreflex in the saline-treated group (hypoxemic vs normoxemic rapid eye movement sleep: 4.37 ± 2.48 vs 2.72 ± 0.83; P < 0.05; hypoxemic vs normoxemic NREM sleep: 4.30 ± 1.47 vs 3.15 ± 0.83; P < 0.001). Magnesium sulfate decreased the baroreflex in the hypoxemic fetuses (magnesium sulfate hypoxemic vs. control normoxemic fetuses: 1.42 ± 0.92 vs 3.15 ± 0.83, P < 0.05).

CONCLUSION

The hypoxemic fetal sheep, from the ewes that were receiving magnesium sulfate, showed a significantly reduced in the baroreflex response. In clinical practice, baroreflex-related decelerations in hypoxemic fetuses of mothers receiving magnesium sulfate should be carefully interpreted.

Magnesium Sulfate Mitigates the Progression of Monocrotaline Pulmonary Hypertension in Rats

We investigated whether magnesium sulfate (MgSO₄) mitigated pulmonary hypertension progression in rats. Pulmonary hypertension was induced by a single intraperitoneal injection of monocrotaline (60 mg/kg). MgSO₄ (100 mg/kg) was intraperitoneally administered daily for 3 weeks, from the seventh day after monocrotaline injection. Adult male rats were randomized into monocrotaline (MCT) or monocrotaline plus MgSO₄ (MM) groups (n = 15 per group); control groups were maintained simultaneously. For analysis, surviving rats were euthanized on the 28^th day after receiving monocrotaline. The survival rate was higher in the MM group than in the MCT group (100% versus 73.3%, p = 0.043). Levels of pulmonary artery wall thickening, α-smooth muscle actin upregulation, right ventricular systolic pressure increase, and right ventricular hypertrophy were lower in the MM group than in the MCT group (all p < 0.05). Levels of lipid peroxidation, mitochondrial injury, inflammasomes and cytokine upregulation, and apoptosis in the lungs and right ventricle were lower in the MM group than in the MCT group (all p < 0.05). Notably, the mitigation effects of MgSO₄ on pulmonary artery wall thickening and right ventricular hypertrophy were counteracted by exogenous calcium chloride. In conclusion, MgSO₄ mitigates pulmonary hypertension progression, possibly by antagonizing calcium.

Magnesium sulfate - An effective agent could delay the progression of fulminant malignant hyperthermia

Malignant hyperthermia (MH) is a life-threatening disease that occurs during general anaesthesia following exposure to succinylcholine (SCh), a depolarizing muscle relaxant, and volatile anaesthetics. Susceptibility to MH most commonly arises from mutations in the RyR1 gene, the Ca²⁺ release channel of skeletal muscle. Fulminant MH (f-MH) is the most dangerous form of MH, which presents a hypermetabolic cascade state, including very high temperature and carbon dioxide production, increased heart rate and oxygen consumption, mixed acidosis, rigid muscles, and rhabdomyolysis. Dantrolene is the only specific drug therapy for MH on the market. Without dantrolene, the reported mortality of f-MH is as high as 42.3%. Based on the participation of catecholamine in the hyperhaemodynamic response of f-MH and the demonstrated effective control of catecholamine release of magnesium sulfate, combined with the fact that magnesium and calcium have opposite effects on muscle contraction, I hypothesized that magnesium sulfate could be a choice for delaying the progression of f-MH while waiting for dantrolene treatment.

Sodium ion transport participates in non-neuronal acetylcholine release in the renal cortex of anesthetized rabbits

This study examined the mechanism of release of endogenous acetylcholine (ACh) in rabbit renal cortex by applying a microdialysis technique. In anesthetized rabbits, a microdialysis probe was implanted into the renal cortex and perfused with Ringer's solution containing high potassium concentration, high sodium concentration, a Na+/K+-ATPase inhibitor (ouabain), or an epithelial Na+ channel blocker (benzamil). Dialysate samples were collected at baseline and during exposure to each agent, and ACh concentrations in the samples were measured by high-performance liquid chromatography. High potassium had no effect on renal ACh release. High sodium increased dialysate ACh concentrations significantly. Ouabain increased dialysate ACh concentration significantly. Benzamil decreased dialysate ACh concentrations significantly both at baseline and under high sodium. The finding that high potassium-induced depolarization does not increase ACh release suggests that endogenous ACh is released in renal cortex mainly by non-neuronal mechanism. Sodium ion transport may be involved in the non-neuronal ACh release.

Magnesium in man: implications for health and disease

Magnesium (Mg(2+)) is an essential ion to the human body, playing an instrumental role in supporting and sustaining health and life. As the second most abundant intracellular cation after potassium, it is involved in over 600 enzymatic reactions including energy metabolism and protein synthesis. Although Mg(2+) availability has been proven to be disturbed during several clinical situations, serum Mg(2+) values are not generally determined in patients. This review aims to provide an overview of the function of Mg(2+) in human health and disease. In short, Mg(2+) plays an important physiological role particularly in the brain, heart, and skeletal muscles. Moreover, Mg(2+) supplementation has been shown to be beneficial in treatment of, among others, preeclampsia, migraine, depression, coronary artery disease, and asthma. Over the last decade, several hereditary forms of hypomagnesemia have been deciphered, including mutations in transient receptor potential melastatin type 6 (TRPM6), claudin 16, and cyclin M2 (CNNM2). Recently, mutations in Mg(2+) transporter 1 (MagT1) were linked to T-cell deficiency underlining the important role of Mg(2+) in cell viability. Moreover, hypomagnesemia can be the consequence of the use of certain types of drugs, such as diuretics, epidermal growth factor receptor inhibitors, calcineurin inhibitors, and proton pump inhibitors. This review provides an extensive and comprehensive overview of Mg(2+) research over the last few decades, focusing on the regulation of Mg(2+) homeostasis in the intestine, kidney, and bone and disturbances which may result in hypomagnesemia.