Roles of the Kv1.2, Kv1.5, Kv2.1 potassium channels in hypoxia pulmonary vasoconstriction

AIM: To determine the role of Kv1.2, Kv1.5, Kv2.1 in the hypoxia pulmonary vasoconstriction (HPV). METHODS: Male Wistar rats were divided into two groups: normoxic group and hypoxic group. The single smooth muscle cell was obtained from pulmonary artery of Wistar rats with acute enzymatic digestion method. The conventional whole-cell patch clamp technique was used to record the resting membrane potential (Em) and the potassium currents of voltage-gated potassium channel (IKv) in rat pulmonary arterial smooth muscle cells (PASMC). Intracellular application of Kv1.2/Kv1.5/Kv2.1 antibodies (1∶125) was conducted through the whole-cell patch clamp system. RESULTS: ① Em of PASMC was depolarized after 24 h hypoxia compared with that of control cells . IKv of PASMC was decreased after 24 h hypoxia, . ② The mixture of Kv1.2/Kv1.5/Kv2.1 antibodies depolarized Em and inhibited IKv in PASMC from normoxic rat, whereas the mixture of Kir2.1/Kir2.3/Kir4.1 antibodies had no effects on them. ③ The mixture of Kv1.2/Kv1.5/Kv2.1 antibodies and the mixture of Kir2.1/Kir2.3/Kir4.1 antibodies had no effects on IKv and Em from rats hypoxic for 24 h. CONCLUSION: Kv1.2, Kv1.5, Kv2.1 might be oxygen sensitive potassium channels which mediated HPV.     

Expression of the hepatitis B surface antigen (HbsAg) under the control of mMT-I promoter in transgenic mice can be induced by zinc sulphate, dexamethasone and lipopolysaccharide

SUMMARY: Metallothionein genes can be induced in vivo by heavy metals, glucocorticoids, and toxins. In all transgenic mice carrying the MT-I promoter, that have been reported so far, induction by glucocorticoids failed. This study reports two mouse lines, transgenic for the murine MT-I-HBV (hepatitis B virus; map position site: 30-1986) construct, which secrete the viral surface antigen (HBsAg) in their serum. In both lines, males produce more HBsAg than females, and in all cases the MT-I promoter can be induced by dexamethasone, lipopolysaccharide (LPS), and heavy metals. A glucocorticoid-responsive element, which is situated in the HBV fragment used, can explain the dexamethasone induction of the MT-I promoter. ZUSAMMENFASSUNG: Expression des Hepatitis B oberfl?chen Antigens (HBsAg) unter Kontrolle des mMT-I Promoters kann in transgenen M?usen durch Zink Sulfat, Dexamethason und Lipopolysacchariden induziert werden Metallothioneingene werden in vivo durch Schwermetalle, Glucocorticoide und Toxine induziert. Soweit bisher bekannt, konnte jedoch in transgenen M?usen mit dem MT-I-Promotor keine Expression durch Glucocorticioide beobachtet werden. Wir berichten hier von zwei transgenen M?uselinien mit dem murinen MT-I-Promotor, der das Oberfl?chenantigen des Hepatitis B Virus (HbsAg, map position site 30-1986) exprimierte. In beiden Linien produzierten die m?nnlichen Tiere mehr HBsAg im Blutserum als die weiblichen. Ohne Ausnahme reagierte der MT-I-Promotor bei Applikation von Dexamethason, Lipopolysaccharid (LPS) und Schwermetall. Ein Glucocorticoid-responsives Element in den HBV-Sequenzen kann die Induktion des MT-I-Promotors erkl?ren.     

Isobaric (gasless) laparoscopic liver and kidney biopsy in standing steers

The purpose of the current study was to investigate the suitability of an isobaric laparoscopic procedure, using a single port, for obtaining serial kidney and liver biopsy samples from standing steers. The samples were used in support of a pharmacokinetic tissue–fluid correlation study. Laparoscopic access was performed 3 times in each of 8 healthy Holstein steers, alternating from the right side to the left side and then to the right side again. The surgery was performed in standing stocks after the animals were given 3 doses of sulfadimethoxine sulfate intravenously and fasted for at least 18 h. Sedation and analgesia were achieved with acepromazine and xylazine. Lidocaine 2% was injected at the center of the paralumbar fossa (left or right), and an incision was made for introduction of a trocar–cannula assembly. Room air was allowed to enter the abdomen through the cannula at the time of insertion. Once the peritoneal cavity was reached, an operating endoscope was inserted. No pressurized insufflation was performed. A biopsy forceps was introduced into the operating channel of the endoscope to obtain a 100-mg kidney or liver sample. No complications were encountered. The 24 laparoscopic procedures provided 24 kidney and 16 liver samples. The results suggest that the isobaric (gasless) single-port laparoscopic technique is feasible for kidney and liver biopsy on standing steers. The procedure can be performed in a reliable and efficient manner in the sedated standing bovine.     

Decomposition of N-labelled maize leaves in soil affected by endogeic geophagous Aporrectodea caliginosa

A microcosm experiment was carried out for 56 days at 12 °C to evaluate the feeding effects of the endogeic geophagous earthworm species Aporrectodea caliginosa on the microbial use of ¹⁵N-labelled maize leaves (Zea mays) added as 5 mm particles equivalent to 1 mg C and 57 μg N g⁻¹ soil. The dry weight of A. caliginosa biomass decreased in the no-maize treatment by 10% during the incubation and increased in the maize leaf treatments by 18%. Roughly 5% and 10% of the added maize leaf-C and leaf-N, respectively, were incorporated into the biomass of A. caliginosa. About 29% and 33% of the added maize leaf-C were mineralised to CO₂ in the no-earthworm and earthworm treatments, respectively. The presence of A. caliginosa significantly increased soil-derived CO₂ production by 90 μg g⁻¹ soil in the no-maize and maize leaf treatments, but increased the maize-derived CO₂ production only by 40 μg g⁻¹ soil. About 10.5% of maize leaf-C and leaf-N was incorporated into the soil microbial biomass in the absence of earthworms, but only 6% of the maize leaf-C and 3% of the maize leaf-N in the presence of earthworms. A. caliginosa preferentially fed on N rich, maize leaf-colonizing microorganisms to meet its N demand. This led to a significantly increased C/N ratio of the unconsumed microbial biomass in soil. The ergosterol-to-microbial biomass C ratio was not significantly decreased by the presence of earthworms. A. caliginosa did not directly contribute to comminution of plant residues, as indicated by the absence of any effects on the contents of the different particulate organic matter fractions, but mainly to grazing of residue-colonizing microorganisms, increasing their turnover considerably.     

Effect of H2O2 on voltage-gated potassium channels in rat pulmonary artery smooth muscle cells

AIM:To determine the effect of hydrogen peroxide (H₂O₂) on voltage-gated potassium channel currents (IKv) in pulmonary vascular smooth muscle cells (PASMCs). METHODS:Using whole cell patch-clamp technique, IKv was recorded in freshly isolated rat PASMCs with acute enzymatic digestion method. The effect of hydrogen peroxide on IKv in PASMCs was investigated in normoxia. RESULTS:IKv in PASMCs was increased significantly by H₂O₂ and the increase depended on the concentration in normoxia. Current-voltage relationship curve shifted to the left. CONCLUSION:Hydrogen peroxide is an important K+ channel opener.     

非病毒性鸡呼吸道疾病

呼吸道疾病可造成严重的经济损失，对受害鸡群的治疗常常很成问题。因此，对呼吸道疾病的临床症状，诊断方法、预防方法以及治疗都必须 有充分的了解，本叙述了非病毒性鸡呼吸道疾病。