Effects of neferine on Kv4.3 channels expressed in HEK293 cells and ex vivo electrophysiology of rabbit hearts.

AIM: Neferine is an isoquinoline alkaloid isolated from seed embryos of Nelumbo nucifera (Gaertn), which has a variety of biological activities. In this study we examined the effects of neferine on Kv4.3 channels, a major contributor to the transient outward current (I(to)) in rabbit heart, and on ex vivo electrophysiology of rabbit hearts. METHODS: Whole-cell Kv4.3 currents were recorded in HEK293 cells expressing human cardiac Kv4.3 channels using patch-clamp technique. Arterially perfused wedges of rabbit left ventricles (LV) were prepared, and transmembrane action potentials were simultaneously recorded from epicardial (Epi) and endocardial (Endo) sites with floating microelectrodes together with transmural electrocardiography (ECG). RESULTS: Neferine (0.1-100 µmol/L) dose-dependently and reversibly inhibited Kv4.3 currents (the IC50 value was 8.437 µmol/L, and the maximal inhibition at 100 µmol/L was 44.12%). Neferine (10 µmol/L) caused a positive shift of the steady-state activation curve of Kv4.3 currents, and a negative shift of the steady-state inactivation curve. Furthermore, neferine (10 µmol/L) accelerated the inactivation but not the activation of Kv4.3 currents, and markedly slowed the recovery of Kv4.3 currents from inactivation. Neferine-induced blocking of Kv4.3 currents was frequency-dependent. In arterially perfused wedges of rabbit LV, neferine (1, 3, and 10 µmol/L) dose-dependently prolonged the QT intervals and action potential durations (APD) at both Epi and Endo sites, and caused dramatic increase of APD10 at Epi sites. CONCLUSION: Neferine inhibits Kv4.3 channels likely by blocking the open state and inactivating state channels, which contributes to neferine-induced dramatic increase of APD10 at Epi sites of rabbit heart.

Protective effects of the calcium-channel blocker flunarizine on crush injury of sciatic nerves in a rat model.

BACKGROUND: Neural damage can be mitigated by calcium-channel blockers (CCBs). However, the mechanism of action of CCBs is not yet fully understood. Objective : To investigate the mechanism of action and efficacy of CCB, flunarizine in restoring neural function after crush injury to the nerves. MATERIALS AND METHODS: The sciatic nerves of rats were crushed using pincers to establish the model for crush injury. Two hundred and eighty-eight Sprague-Dawley (SD) rats were randomly divided into sham-operated, saline, and low-dose flunarizine and high-dose flunarizine (FI and FII) groups. The expression of the protein c-fos in the dorsal root ganglia (DRG) after crush injury to the sciatic nerves was investigated by using reverse transcription-polymerase chain reaction (RT-PCR) and Western blot. The effect of flunarizine on c-fos expression and its efficacy in restoring neural function was evaluated. RESULTS: The c-fos messenger ribonucleic acid (mRNA) and protein expression in FI and FII groups was significantly lower than in the saline group and was the least in the FII group. Nerve-conduction velocity was increased in the order of: saline < FI< FII< sham-operated. There was no significant difference in the nerve-conduction velocity in the sham-operated and FII groups (P>.05). CONCLUSIONS: When administered after crush injury to peripheral nerves, flunarizine may protect neurons with lesions from further damage and improve neural function by downregulating c-fos expression.

Evaluation of pharmacokinetics of 4-borono-2-(18)F-fluoro-L-phenylalanine for boron neutron capture therapy in a glioma-bearing rat model with hyperosmolar blood-brain barrier disruption.

UNLABELLED: This study evaluated the pharmacokinetics and biodistribution of 4-borono-2-(18)F-fluoro-l-phenylalanine ((18)F-FBPA) after intracarotid injection and with blood-brain barrier disruption (BBB-D) in F98 glioma-bearing F344 rats. The pharmacokinetics of l-p-boronophenylalanine (BPA) and (18)F-FBPA following different administration routes were compared to demonstrate the optimal delivery route and the time period for thermal neutron irradiation. METHODS: F98 glioma-bearing rats were injected intravenously or intracarotidly with (18)F-FBPA and BPA and with or without mannitol-induced hyperosmotic BBB-D. The boron concentration and (18)F radioactivity in tissues were determined by invasive (inductively coupled plasma mass spectroscopy, gamma-counting) and noninvasive PET methods. RESULTS: The biodistributions of (18)F-FBPA and BPA in F98 glioma-bearing rats were similar after intracarotid administration with BBB-D. The accumulation of BPA and (18)F-FBPA in brain tumor and the tumor-to-ipsilateral brain ratios were the highest after intracarotid injection with BBB-D, whereas the retention of boron drugs in contralateral brains exhibited only nonsignificant differences compared with those after intracarotid injection without BBB-D and intravenous injection. The high boron concentration in brain tumor (76.6 mug/g) and the high tumor-to-ipsilateral brain ratio (6.3) may afford enough radiation doses to destroy the tumor cells while sparing the normal tissues in boron neutron capture therapy. The pharmacokinetic parameters of k(el), k(12), k(21), and V(1) for intracarotid injection of (18)F-FBPA with BBB-D derived from the open 2-compartment model are 0.0206 +/- 0.0018 min(-1), 0.0260 +/- 0.0016 min(-1), 0.0039 +/- 0.0003 min(-1), and 3.1 +/- 0.1 mL, respectively. The effect of BBB-D varied depending on the anesthetic agents used and the anesthetic conditions. A smaller degree of BBB-D and, thus, lower boron concentrations in tumor and ipsilateral brain were observed under isoflurane anesthesia than under ketamine anesthesia. The k(12)/k(21) ratio may serve as a good indication for evaluating the extent of BBB-D, tumor uptake, and tumor-to-brain ratio after intracarotid injection of boron compounds. CONCLUSION: Our findings provide important information for establishing an optimal treatment protocol when intracarotid injection with BPA after BBB-D is applied in clinical boron neutron capture therapy.

A pilot study comparing the clinical effects of Jia-Wey Shiau-Yau San, a traditional Chinese herbal prescription, and a continuous combined hormone replacement therapy in postmenopausal women with climacteric symptoms.

OBJECTIVES: Interest in use of alternative remedies for managing menopausal symptoms is increasing exponentially during these years. Jia-Wey Shiau-Yau San (JWSYS), one of the traditional Chinese herbal prescriptions, is a famous herbal remedy used for the management of various menopausal-related symptoms. A randomized, controlled pilot study was performed to evaluate the clinical effects of JWSYS compared with those of a continuous combined hormone replacement therapy, Premelle, on quality of life in non-hysterectomized postmenopausal women. METHODS: The present trial compared the effect of a l6-week treatment with JWSYS or HRT (Premelle) in postmenopausal women with climacteric symptoms. The Greene Climacteric Scale was used to assess the clinical effects at baseline and after 16 weeks' treatment with either JWSYS or Premelle. The physiological parameters, such as follicle-stimulating hormone and estradiol levels, were also recorded at the same time points. RESULTS: The results showed that JWSYS had a relatively lower discontinuation rate due to adverse effects, in particular the bleeding and breast tenderness. Both JWSYS and Premelle effectively alleviated most of the menopausal symptoms with no significant differences between treatment groups, whereas the beneficial effects of JWSYS were not mediated by hormone replacement-like effects. Moreover, JWSYS showed a good compliance and safety without estrogenic effects and metabolic alterations. CONCLUSIONS: It was suggested that JWSYS was a safe and efficacious therapy and might be an alternative choice for relief of climacteric symptoms in postmenopausal women. However, the exact efficacy and clinical roles of JWSYS have not been convincingly demonstrated in this study because of the blinding approach and some statistical concerns, and only the possibility of its efficacy has been raised. Therefore, a blinding trial with more patient numbers to evaluate the efficacy of JWSYS deserves further study.

Pharmacokinetic interactions between carbamazepine and the traditional Chinese medicine Paeoniae Radix.

The present study was conducted to evaluate the effects of Paeoniae Radix (PR), one of the most famous tonic traditional Chinese medicines, on the pharmacokinetics of carbamazepine (CBZ) in rats and to determine the possible interactions between PR and CBZ. The significant decrease in Tmax indicated that simultaneous oral administration of PR contributed to more rapid absorption of CBZ. It is suggested that the faster absorption of CBZ might lead to the rapid onset of its clinical effect. There were no significant differences in maximum concentration (Cmax), area under the plasma concentration-time curve (AUC), half-life (t1/2), mean residence time (MRT), clearance/bioavailability (CL/F), and apparent volume of distribution/bioavailability (Vd/F) of CBZ between the two groups, showing that PR did not significantly affect the absorption extent, distribution, metabolism, and elimination of CBZ. A significant decrease in protein binding rate was found when CBZ was coadministered with PR. Further studies are in progress to clarify the clinical significance and the mechanism underlying the effects of PR on the protein binding of CBZ observed in the present study.