Propofol inhibits volume-sensitive chloride channels in human coronary artery smooth muscle cells

Propofol-associated QTc prolongation

OBJECTIVES

Propofol is a preferred agent for sedation in patients in the intensive care unit (ICU) due, in part, to its established safety profile. Despite this, recent case reports have suggested a potential for prolongation of the corrected QT interval (QTc) in ICU patients receiving propofol, though limited empirical work has been conducted to evaluate this association. As such, the purpose of this study was to assess the relationship between propofol infusion and QTc prolongation in a historical cohort of ICU patients.

METHODS

A single-center, historical, observational, pre-post cohort analysis of medical records from admitted patients ⩾18 years old with cardiovascular disease was conducted, involving cases who received propofol infusion for ⩾3 hours with sequential electrocardiogram monitoring from 2006 to 2012. A multivariable, generalized linear model regression was employed to assess the primary outcome of on-propofol QTc interval (QTc2), controlling for various demographic and clinical factors.

RESULTS

A total of 96 patients met inclusion criteria, averaging 56.1 ± 14.1 years of age and 86.1 ± 25.0 kg, with 37.5% being female. A mean prolongation in QTc interval of 30.4 ± 55.5 ms (p < 0.001) was observed during the propofol infusion, with 43.8% of cases exhibiting an on-infusion QTc2 of ⩾ 500 ms. Regression analyses suggested that prolongation in on-propofol QTc was independently associated with baseline QTc interval and amiodarone use, while weight as inversely associated with QTc2 (p < 0.05).

CONCLUSION

This historical cohort analysis of adult ICU patients receiving propofol suggests that on-infusion QTc prolongation was associated with increasing baseline QTc interval and with amiodarone use. Further research is needed to evaluate the clinical significance and cause-and-effect relationship between potential QTc changes and propofol use in the ICU.

Propofol-induced relaxation of rat aorta is altered by aging

BACKGROUND

Propofol causes vasodilation via endothelium-dependent and -independent mechanisms. Because endothelial function is impaired with aging, the effects of propofol on endothelium-dependent vasodilation might be altered by aging. The aim of this study was thus to determine the effects of aging on vascular responses to propofol.

METHODS

Young (4-6 weeks old) or adult (16-25 weeks old) rats were anesthetized with sevoflurane. The thoracic aorta was dissected and cut into pieces 3-4 mm in length. In some rings, the endothelium was deliberately removed. The ring segment of the aorta was mounted for isometric force recording at a resting tension of 0.5-1.0 g in a 2 ml organ bath, containing Krebs-Ringer bicarbonate buffer. Arteries were precontracted with phenylephrine, and the function of endothelium was confirmed with acetylcholine. Then, we studied the concentration-dependent effects of propofol in endothelium-intact (control group) and -denuded aortic rings (denuded group), as well as those treated with N(ω)-nitro-L-arginine methylester (L-NAME group).

RESULTS

Relaxation due to propofol was observed in the control groups of both young and adult rats in a concentration-dependent manner, but the magnitude of relaxation was significantly greater in young rats. In addition, in young rats, relaxation due to propofol was significantly and equally reduced in both L-NAME and denuded groups at all propofol concentrations that we studied (10(-6)-10(-3) M). In adult rats, relaxation due to propofol was quite similar between control and L-NAME groups at all propofol concentrations, whereas it was significantly reduced in the denuded group.

CONCLUSION

These results suggest that endothelium-derived nitric oxide plays an important role in propofol-induced vasodilation in young rats, but not in adult rats.

QSAR Studies on the Anesthetic Action of Some Polyhalogenated Ethers

There has been an on-going debate about the mode of action of general anesthetics and until now, many sites have been postulated as target site for action of these compounds. Here, some quantum chemical-based quantitative structure-activity relationship (QSAR) models were developed for a set of polyhalogenated ethers in order to investigate the aspects of their anesthetic action, which is not completely defined yet, although some hypotheses have been suggested. A data set including 25 polyhalogenated methyl ethyl ethers were selected, and different descriptors were calculated for each molecule using density functional theory calculations, and subsequently some multilinear QSAR models were built by using different sets of the calculated molecular descriptors. The result showed that polar (polarizability) and non-polar (log P) parameters have mixed role on the anesthetic activity i.e. models with high statistical quality were obtained in combination with these two parameters. Also a good model between anesthetic action and electrostatic potentials was obtained, which may imply the important role of electronic interactions in the anesthetic activity of the compounds. Finally, a four-parametric QSAR model containing log P, molecular polarizability, most positive charge and an electrostatic potential parameters was obtained, which indicated that the anesthetic action of the polyhaloganted ethers may be proceeded through lipophilic, steric and columbic interactions.