Propofol, an Anesthetic Agent, Inhibits HCN Channels through the Allosteric Modulation of the cAMP-Dependent Gating Mechanism

Suppressive effect of the anesthetic propofol on the T cell function and T cell-dependent immune responses

General anesthesia is thought to suppress the immune system and negatively affect postoperative infection and the long-term prognosis of cancer. However, the mechanism underlying immunosuppression induced by general anesthetics remains unclear. In this study, we focused on propofol, which is widely used for sedation under general anesthesia and intensive care and examined its effects on the T cell function and T cell-dependent immune responses. We found that propofol suppressed T cell glycolytic metabolism, differentiation into effector T cells, and cytokine production by effector T cells. CD8 T cells activated and differentiated into effector cells in the presence of propofol in vitro showed reduced antitumor activity. Furthermore, propofol treatment suppressed the increase in the number of antigen-specific CD8 T cells during Listeria infection. In contrast, the administration of propofol improved inflammatory conditions in mouse models of inflammatory diseases, such as OVA-induced allergic airway inflammation, hapten-induced contact dermatitis, and experimental allergic encephalomyelitis. These results suggest that propofol may reduce tumor and infectious immunity by suppressing the T cell function and T cell-dependent immune responses while improving the pathogenesis and prognosis of chronic inflammatory diseases by suppressing inflammation.

Comparison of postoperative pain in children after maintenance anaesthesia with propofol or sevoflurane: a systematic review and meta-analysis

BACKGROUND

Propofol and sevoflurane are two of the most commonly used anaesthetics for paediatric surgery. Data from some clinical trials suggest that postoperative pain incidence is lower when propofol is used for maintenance of anaesthesia compared with sevoflurane, although this is not clear.

METHODS

This meta-analysis compared postoperative pain following maintenance of anaesthesia with propofol or sevoflurane in paediatric surgeries. PubMed Medline, Embase, Scopus, Web of Science and Cochrane Library were searched for randomised controlled trials (RCTs) that compared postoperative pain between sevoflurane and propofol anaesthesia in children. After quality assessment, a meta-analysis was carried out using bias-adjusted inverse heterogeneity methods, heterogeneity using I2 and publication bias using Doi plots.

RESULTS

In total, 13 RCTs with 1174 children were included. The overall synthesis suggested nearly two-fold higher odds of overall postoperative pain in the sevoflurane group compared with the propofol group (odds ratio [OR] 1.88, 95% confidence interval [CI] 1.12-3.15, I2=58.2%). Further, children in the sevoflurane group had higher odds of having higher pain scores (OR 3.18, 95% CI 1.83-5.53, I2=20.9%), and a 60% increase in the odds of requiring postoperative rescue analgesia compared with propofol (OR 1.60, 95% CI 0.89-2.88, I2=58.2%).

CONCLUSIONS

Children maintained on inhalational sevoflurane had higher odds of postoperative pain compared with those maintained on propofol. The results also suggest that sevoflurane is associated with higher odds of needing postoperative rescue analgesia compared with propofol.

REGISTRATION

The protocol for this systematic review and meta-analysis was registered on the International Prospective Register of Systematic Reviews (PROSPERO) with registration ID CRD42023445913.

The Dysfunction of Ca2+ Channels in Hereditary and Chronic Human Heart Diseases and Experimental Animal Models

Chronic heart diseases, such as coronary heart disease, heart failure, secondary arterial hypertension, and dilated and hypertrophic cardiomyopathies, are widespread and have a fairly high incidence of mortality and disability. Most of these diseases are characterized by cardiac arrhythmias, conduction, and contractility disorders. Additionally, interruption of the electrical activity of the heart, the appearance of extensive ectopic foci, and heart failure are all symptoms of a number of severe hereditary diseases. The molecular mechanisms leading to the development of heart diseases are associated with impaired permeability and excitability of cell membranes and are mainly caused by the dysfunction of cardiac Ca2+ channels. Over the past 50 years, more than 100 varieties of ion channels have been found in the cardiovascular cells. The relationship between the activity of these channels and cardiac pathology, as well as the general cellular biological function, has been intensively studied on several cell types and experimental animal models in vivo and in situ. In this review, I discuss the origin of genetic Ca2+ channelopathies of L- and T-type voltage-gated calcium channels in humans and the role of the non-genetic dysfunctions of Ca2+ channels of various types: L-, R-, and T-type voltage-gated calcium channels, RyR2, including Ca2+ permeable nonselective cation hyperpolarization-activated cyclic nucleotide-gated (HCN), and transient receptor potential (TRP) channels, in the development of cardiac pathology in humans, as well as various aspects of promising experimental studies of the dysfunctions of these channels performed on animal models or in vitro.

Recent advances in the study of anesthesia-and analgesia-related mechanisms of S-ketamine

Ketamine is a racemic mixture of equal amounts of R-ketamine and S-ketamine and is well known to anesthesiologists for its unique dissociative anesthetic properties. The pharmacological properties of ketamine, namely, its sympathetic excitation, mild respiratory depression, and potent analgesia, are still highly valued in its use as an anesthetic for some patients. In particular, since its advent, S-ketamine has been widely used as an anesthetic in many countries due to its increased affinity for NMDA receptors and its enhanced anesthetic and analgesic effects. However, the anesthetic and analgesic mechanisms of S-ketamine are not fully understood. In addition to antagonizing NMDA receptors, a variety of other receptors or channels may be involved, but there are no relevant mechanistic summaries in the literature. Therefore, the purpose of this paper is to review the mechanisms of action of S-ketamine on relevant receptors and systems in the body that result in its pharmacological properties, such as anesthesia and analgesia, with the aim of providing a reference for its clinical applications and research.

The Potential Antidepressant Compound Org 34167 Modulates HCN Channels Via a Novel Mode of Action

Org 34167 is a small molecule hyperpolarization-activated cyclic nucleotide-gated (HCN) channel modulator that has been trialed in humans for its potential antidepressant activity. The precise action of Org 34167 is not fully understood. Here we use two-electrode voltage clamp recordings and an allosteric model to explore the interaction of Org 34167 with human HCN1 channels. The impact of Org 34167 on channel function included a hyperpolarizing shift in activation voltage dependence and a slowing of activation kinetics. Furthermore, a reduction in the maximum open probability at extreme hyperpolarization argued for an additional voltage-independent mechanism. Org 34167 had a similar impact on a truncated HCN1 channel lacking the C-terminal nucleotide binding domain, thus ruling out an interaction with this domain. Fitting a gating model, derived from a 10-state allosteric scheme, predicted that Org 34167 strongly reduced the equilibrium constant for the voltage-independent pore domain to favor a closed pore, as well as reducing the voltage sensing domain-pore domain coupling and shifting the zero voltage equilibrium constant of the voltage sensing domain to favor the inactive state. SIGNIFICANCE STATEMENT: The brain penetrant small molecule Org 34167 has been reported to have an antidepressant action by targeting HCN channels; however, its mode of action is unknown. We used heterologously expressed human HCN1 channels to show that Org 34167 inhibits channel activity by modulating kinetic parameters associated with the channel pore domain, voltage sensing domain, and interdomain coupling.