Tea polyphenols promote cardiac function and energy metabolism in ex vivo rat heart with ischemic/reperfusion injury and inhibit calcium inward current in cultured rat cardiac myocytes / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the protective effects of tea polyphenols (TP) against myocardial ischemia/reperfusion (IR) injuries and explore the possible mechanisms.</p><p><b>METHODS</b>Langendorff-perfused rat hearts were subjected to ischemia for 30 min followed by reperfusion for another 30 min. Myocardial function indices were measured by a left ventricular cannula via a pressure transducer connected to the polygraph in isolated Langendorff hearts and energy metabolism was measured using (31)P nuclear magnetic resonance (NMR) spectroscopy. Whole-cell atch-clamp technique was used to record calcium inward current (I(Ca-L)) in cultured rat cardiac myocytes.</p><p><b>RESULTS</b>Compared with the control hearts, the ex vivo rat hearts with 2.5 mg/L TP treatment showed significantly increased left ventricular developed pressure (LVDP), maximal rise rate of LVDP (+dp/d(tmax)), maximal fall rate of LVDP (-dp/dt(max)), and coronary flow (CF) (P<0.05). During both cardiac ischemia and reperfusion phase, ATP and PCr levels were elevated significantly in TP-treated hearts compared with those in the control hearts (P<0.05). In cultured rat cardiac myocytes, ICa-L was remarkably decreased by TP at the doses of 2.5 and 5.0 mg/L (P<0.01).</p><p><b>CONCLUSION</b>Our results support a possible protective role of TP against myocardial IR injury by improving myocardial energy metabolism and inhibiting I(Ca-L) in the cardiac myocytes.</p>

Pharmacokinetics of 6beta-naltrexol after single and multiple intramuscular injections in Beagle dogs / 药学学报

The pharmacokinetics of 6beta-naltrexol (6beta-NOL) following single intramuscular administration and multiple intramuscular injection once per day for seven days was studied in 4 Beagle dogs. Plasma concentration of 6beta-NOL in dogs was analyzed by a combination of high performance liquid chromatography (HPLC) and electrochemical detection with naloxone (NLX) as internal standard. After single intramuscular injection of 0.2 mg x kg(-1) 6beta-NOL, the plasma concentration-time curve of the drug was found to fit to a two compartment model with first-order absorption. The main parameters of single dosing were as follows: t1/2alpha was (0.26 +/- 0.23) h, t1/2beta was (4.77 +/- 1.65) h, C(max) was (81.65 +/- 5.61) ng x mL(-1), t(peak) was (0.27 +/- 0.07) h, CL(s) was (1.20 +/- 0.06) L x kg(-1) x h(-1), V/F(c) was (1.94 +/- 0.15) L x kg(-1), and AUC(0-t) was (166.82 +/- 7.68) ng x h x mL(-1), separately. After multiple intramuscular injection of 0.2 mg x kg(-1) 6beta-NOL once per day for seven days, the plasma concentration-time curve of the drug fitted to a two compartment model with first-order absorption too. The main parameters of the last dosing were as follows: t1/2alpha was (0.19 +/- 0.18) h, t1/2beta was (5.79 +/- 1.50) h, C(max) was (79.82 +/- 10.5) ng x mL(-1), t(peak) was (0.18 +/- 0.08) h, CL(s) was (1.12 +/- 0.07) L x kg(-1) x h(-1), V/F(c) was (2.10 +/- 0.27) L x kg(-1), and AUC(0-t) was (173.23 +/- 9.49) ng x h x mL(-1), separately. The difference of the parameters between the first and the last dosing was not significant, showing that the plasma kinetics of 6beta-naltrexol was not changed after multiple administrations. In the course of multiple administration, the peak and valley concentration of plasma 6beta-naltrexol were (79.03 +/- 10.3) and (1.50 +/- 0.93) ng x mL(-1), respectively. No clear adverse events were noted during this study. These results showed that plasma 6beta-naltrexol fits to a two compartment model with first-order absorption in dog after intramuscular administration and their pharmacokinetic parameters were reported. There was no remarkable change on plasma pharmacokinetics of 6beta-naltrexol after multiple intramuscular administrations.

Effects of beta-lactam antibiotics on development of tolerance and dependence to morphine / 药学学报

In order to identify ceftriaxone and its analogs whether has the function of anti-tolerance of morphine and study the dose-effect relation of ceftriaxone in mice, hot plate method to measure pain threshold of mouse and naloxone withdrawal models were carried out and compared with normal saline group. Ceftriaxone and cefotaxime had the effect of anti-tolerance and anti-dependence of morphine notably. And ceftriaxone has the effect of anti-tolerance of morphine in a dose dependent manner.