The differential effects of midazolam and diazepam on intracellular Ca2+ transients and contraction in adult rat ventricular myocytes

Midazolam suppresses ischemia/reperfusion-induced cardiomyocyte apoptosis by inhibiting the JNK/p38 MAPK signaling pathway

Myocardial ischemia/reperfusion (I/R) injury causes irreversible injury to the heart, thereby causing acute myocardial infarction. Midazolam is a benzodiazepine commonly utilized in anesthesia and intensive care. Research has indicated that midazolam plays a critical role in many diseases; however, the function of midazolam in myocardial injury induced by I/R still needs further investigation. The infarct size and damage to the heart tissues were examined through 2,3,5-triphenyl tetrazolium chloride (TTC) staining and hematoxylin and eosin staining. The creatine kinase-myocardial band isoenzyme, lactate dehydrogenase, and aspartate aminotransferase levels were tested using commercial kits. Cell apoptosis was determined through TUNEL staining or flow cytometry assays. Bax, Bcl-2, cleaved caspase-3, phospho-38 (p-p38), p38, p-JNK, JNK, extracellular signal-regulated kinases (ERK), and p-ERK expression was examined through Western blot. In our study, midazolam was shown to suppress the infarct size and heart tissue damage and reduce myocardial enzyme leakage in I/R rats. Additionally, midazolam was found to retard cardiomyocyte apoptosis in I/R rats. The JNK/p38 MAPK signaling pathway in I/R rats was inhibited by midazolam. Our findings demonstrated that in hypoxia/reoxygenation (H/R) - mediated H9C2 cells, anisomycin abolished the suppressive effects of midazolam on the JNK/p38 MAPK signaling pathway. Next, exploration discovered that anisomycin abolished the cytoprotective effects of midazolam on H/R-treated H9C2 cell apoptosis. In conclusion, this work demonstrated that midazolam retarded I/R-induced cardiomyocyte apoptosis by inhibiting the JNK/p38 MAPK signaling pathway. These results may provide new insight into the treatment of myocardial I/R injury.

Anaesthetic management using remimazolam in a patient with severe aortic stenosis: a case report

Background

The administration of general anaesthesia in patients with aortic stenosis (AS) requires careful attention to haemodynamics. We used remimazolam for the induction and maintenance of anaesthesia in a woman with severe AS undergoing a total mastectomy.

Case presentation

An 81-year-old woman with severe AS was scheduled to undergo a total mastectomy. We decided to administer total intravenous anaesthesia with remimazolam to minimize haemodynamic changes. Although the patient showed transient hypotension after anaesthesia induction, the cardiac index was preserved with a low dose of continuous noradrenaline. The anaesthesia was then safely maintained without a decrease in the patient’s cardiac index.

Conclusions

General anaesthesia using remimazolam preserved cardiac output in this patient; therefore, remimazolam can be safely used to avoid the risk of cardiac suppression in patients with severe AS.

Genetic variants in sex hormone pathways and the risk of type 2 diabetes among African American, Hispanic American, and European American postmenopausal women in the US

BACKGROUND

Sex hormones are implicated in the development of diabetes. However, whether genetic variations in sex hormone pathways (SHPs) contribute to the risk of type 2 diabetes mellitus (T2DM) remains to be determined. This study investigated associations between genetic variations in all candidate genes in SHPs and T2DM risk among a cohort of women participating in the Women's Health Initiative (WHI).

METHODS

Single nucleotide polymorphisms (SNPs) located within 30 kb upstream and downstream of SHP genes were comprehensively examined in 8180 African American, 3498 Hispanic American, and 3147 European American women in the WHI. In addition, whether significant SNPs would be replicated in independent populations was examined.

RESULTS

After adjusting for age, region, and ancestry estimates and correcting for multiple testing, seven SNPs were significantly associated with the risk of T2DM among Hispanic American women were identified in the progesterone receptor (PGR) gene, with rs948516 showing the greatest significance (odds ratio 0.67; 95% confidence interval 0.57-0.78; P = 8.8 × 10^-7 ; false discovery rate, Q = 7.8 × 10^-4 ). These findings were not replicated in other ethnic groups in the WHI or in sex-combined analyses in replication studies.

CONCLUSION

Significant signals were identified implicating the PGR gene in T2DM development in Hispanic American women in the WHI, which are consistent with genome-wide association studies findings linking PGR to glucose homeostasis. Nevertheless, the PGR SNPs-T2DM association was not statistically significant in other ethnic populations. Further studies, especially sex-specific analyses, are needed to confirm the findings and clarify the role of SHPs in T2DM.

Cardiovascular manifestations of sedatives and analgesics in the critical care unit

There are numerous sedatives and analgesics used in critical care medicine today; these medications are used on critically ill patients, many of whom have heart disease, including coronary artery disease or congestive heart failure. The purpose of this review is to recognize the effects of these medications on the heart. Studies that evaluated the effects of sedatives and analgesics on normal individuals or on those with heart disease were reviewed. Current choices for sustained sedation in the critically ill include the benzodiazepines, morphine, propofol, and etomidate. Each of these medications has their particular advantages and disadvantages. Benzodiazepines provide the greatest amnesia and cardiovascular safety but they can cause significant hypotension in the hemodynamically unstable patient. Morphine provides analgesia and cardioprotective activity after ischemia, although the large observational study CRUSADE showed increased mortality rate in those patients with non-ST segment elevation myocardial infarction who received morphine. Propofol is the most easily titratable drug with cardioprotective features, but its use must be accompanied with great attention to possible development of propofol infusion syndrome, which is a deadly disease, especially in patients with head injury and those with septic shock receiving vasopressors. Etomidate has a rapid onset effect and short period of action with great hemodynamic stability even in patients with shock and hypovolemia, but the incidence of adrenal insufficiency during infusion, not bolus doses, may cause deterioration in the circulatory stability. In conclusion, the sedatives and analgesics mentioned here have characteristics that give them a cardiovascular safety profile useful in critically ill patients. However, use of these drugs on an individual basis is dependent on each agent's safety and efficacy.

Effects of L-type Ca2+ channel modulation on direct myocardial effects of diazepam and midazolam in adult rat ventricular myocytes

PURPOSE

Our objective was to determine whether an L-type Ca2+ channel modulation could alter myocardial depression induced by midazolam or diazepam in adult rat ventricular myocytes.

METHODS

Freshly isolated rat ventricular myocytes were loaded with fura-2/AM and field-stimulated (0.3 Hz) at 28 degrees C. Amplitude and timing of intracellular Ca2+ concentration ([Ca2+]i) and myocyte shortening were simultaneously monitored in individual cells.

RESULTS

Midazolam (3-100 microM) caused a decrease in both peak [Ca2+]i and shortening. Diazepam (30, 100 microM) increased myocyte shortening and peak [Ca2+]i; however, higher concentration of diazepam (300 microM) decreased shortening and peak [Ca2+]i. Bay K 8644 (0.01-10 microM), an L-type Ca2+ channel agonist, caused dose-dependent increases in peak [Ca2+]i and shortening. In contrast, verapamil (0.1-50 microM), an L-type Ca(2+) channel antagonist, caused dose-dependent decreases in peak [Ca2+]i and shortening. Dose-response curves to benzodiazepines on peak [Ca2+]i and shortening were not affected by pretreatment with Bay K 8644 (0.1 microM) or verapamil (1 microM). Diazepam (30, 100 microM), but not midazolam (3-30 microM), increased shortening and [Ca2+]i in the presence or absence of L-type Ca2+ channel modulators. Diazepam (30 microM) and midazolam (10 microM) had no effect on peak [Ca2+]i of a caffeine-induced [Ca2+]i transient, which was used as a measure of SR Ca2+ content.

CONCLUSION

Midazolam and diazepam have differential effects on cardiac E-C coupling. Diazepam, but not midazolam, enhances cardiac E-C coupling independent of L-type Ca2+ channel modulation.

Midazolam suppresses thrombin-induced heat shock protein 27 phosphorylation through inhibition of p38 mitogen-activated protein kinase in cardiac myocytes

It has been shown that anesthetics have effects of cardiac preconditioning. Heat shock proteins (HSPs) function as molecular chaperone. Among them, HSP27, a low-molecular-weight HSP, abundantly exist in heart. However, the relationship between anesthetics and HSP27 in heart is not yet clarified. We investigated whether thrombin induces or phosphorylates HSP27 in primary cultured mouse myocytes and the effect of midazolam on the thrombin-stimulated HSP27 phosphorylation and the mechanism behind it. Thrombin time dependently phosphorylated HSP27 at Ser-15 and Ser-85 while having no effect on the levels of HSP27. Midazolam markedly suppressed the thrombin-induced phosphorylation of HSP27 at both Ser-15 and Ser-85. Thrombin induced the phosphorylation of p44/p42 MAP kinase and p38 MAP kinase without affecting stress-activated protein kinase/c-Jun N-terminal kinase. In addition, midazolam attenuated the phosphorylation of thrombin-induced p38 MAP kinase but not that of p44/p42 MAP kinase. SB203580 and PD169316, inhibitors of p38 MAP kinase, suppressed the thrombin-induced phosphorylation of HSP27 at both Ser-15 and Ser-85. These results strongly suggest that thrombin induces the HSP27 phosphorylation at least through the p38 MAP kinase activation in cardiac myocytes and that midazolam inhibits the thrombin-induced HSP27 phosphorylation via suppression of p38 MAP kinase activation.