Effects of intrathecal isoflurane administration on nociception and Fos expression in the rat spinal cord.

BACKGROUND AND OBJECTIVE: Isoflurane has been used as an inhaled anaesthetic for nearly 30 years. Isoflurane inhalation during anaesthesia also produces an anti-nociceptive effect. Whether this occurs at the spinal or supraspinal level remains unknown. With a novel type of liquid isoflurane, the present study examined the effects of intrathecal isoflurane on the nociceptive response and Fos expression in the rat spinal cord. METHODS: Thirty-six rats were randomly assigned to three groups as follows: group A (n = 6), intrathecal physiological saline 50 µl kg⁻¹; and group B and C (n = 6 each), intrathecal isoflurane at doses of 25 µl kg⁻¹ or 50 µl kg⁻¹, respectively. Noxious thermal (Hargreaves test), mechanical (von Frey test) and chemical (formalin 5%, 50 µl) stimuli were applied to a hind paw after intrathecal isoflurane injection to study its anti-nociceptive effect. In addition, the expression of Fos protein and c-fos mRNA in the spinal dorsal horns was detected by immunohistochemistry and real-time reverse transcriptase PCR, respectively. RESULTS: Compared with the physiological saline control, intrathecal isoflurane significantly suppressed spontaneous paw flinches in rats induced by formalin injection and paw withdrawal induced by thermal and mechanical stimuli in a dose-dependent manner. Immunohistochemistry and real-time reverse transcriptase PCR revealed that isoflurane administration inhibited formalin injection-induced c-fos expression in the spinal cord. CONCLUSIONS: These data suggest that isoflurane can exert anti-nociceptive effects at the spinal level by preventing neuronal activation.

Base-promoted aryl-bromine bond cleavage with cobalt(II) porphyrins via a halogen atom transfer mechanism.

Aryl-bromine bonds are successfully cleaved by cobalt(II) porphyrins in basic media to give Co(por)Ar (por = porphyrin) in good yields. Mechanistic studies suggested that the aryl-bromine bond is cleaved through a halogen atom transfer mechanism, which is different from the aryl-halogen bond cleavage mechanism with other group 9 metalloporphyrins.

[Determination of propofol in human serum by improved reversed phase high-performance liquid chromatography with fluorescence detection].

OBJECTIVE: To develop a new high-performance liquid chromatographic (HLPC) method for determination of propofol in human serum. METHODS: Human serum samples were precipitated with 20% perchloric acid and centrifuged to obtain 50 microl of the supernatant for analysis by HPLC coupled with fluorescence detection. The analysis was performed with a C(18) reversed-phase column using a acetonitrile-water (90:10) phase delivered at 1.0 ml/min, with the excitation wavelength of 276 nm and emission wavelength of 310 nm. RESULTS: The calibration curves were linear (r=0.997 5) within the concentration range of 0.05-10 microg/ml, the limit of propofol quantification was 50 ng/ml and the intra- and inter-day precisions were between -/+15%. CONCLUSIONS: The method is accurate, sensitive and simple for propofol determination in clinical anesthesia.