Effect of alcohol on perceived exertion in relation to heart rate and blood lactate

The purpose of the study was to determine whether the perception of exertion is affected by alcohol during physical performance and whether altered self-rating of exertion is the result of an altered perception per se or of an altered physical capacity to perform work. Ten healthy men participated. Each subject was his own control and received an alcohol dose corresponding to 1 g.kg-1 body mass in 40% solution in the experimental session. The exercise test was performed on a cycle ergometer with an initial intensity of 50 W which was increased stepwise by 50 W at 4-min intervals up to near-maximal. The rating of perceived exertion (RPE) did not differ between alcohol and control sessions. Alcohol induced a significant increase in heart rate during exercise at 50 W (delta x = 8 beats.min-1) and at 100 W (delta x = 10 beats.min-1), while the change at higher intensities was insignificant. The systolic blood pressure and the blood lactate concentration were not significantly changed by alcohol. It is concluded that a moderate dose of alcohol does not alter RPE during physical exercise either per se or secondarily to an altered physical capacity to perform work.     

Impact of salt adaptation on esterified fatty acids and cytochrome oxidase in plasma and thylakoid membranes from the cyanobacterium Anacystis nidulans

During adaptation of photoautotrophically growing fresh water cyanobacterium Anacystis nidulans to high salinity the cells showed a pronounced increase of proton-sodium antiporter activity, and of cytochrome c oxidase in isolated and purified plasma membrane. At the same time the concentrations of plasma membrane-bound EDTA-resistant copper and iron (determined by inductively coupled plasma atomic emission spectrometry) rose proportionately, accompanied by an increase in whole cell respiration. In plasma membranes from salt adapted cells lipid/protein ratios were markedly higher than in control cells, levels of esterified saturated and long-chain fatty acids being significantly higher than the respective levels of unsaturated and short-chain fatty acids which explains the higher lipid-phase transition temperatures derived from Arrhenius plots. Immunoblotting of the membrane proteins with antisera raised against the cytochrome c oxidases from Paracoccus denitrificans and A. nidulans gave two cross-reacting bands with apparent molecular weights around 50000 and 30000 (subunits I and II, respectively) which were more pronounced in plasma membranes from salt adapted cells when compared to control cells. The protein pattern of plasma membranes from salt adapted cells also showed the appearance of bands at apparent molecular weights of 44000–48000 and 54000–56000 which might stem from the proton/sodium-antiporter in this membrane.Abbreviations CM cytoplasmic or plasma membrane - ICM intracytoplasmic or thylakoid membrane - cyt cytochrome - DCCD N,N-dicyclohexylcarbodiimide - Hepes N-2-hydroxyethylpiperazine-N-2-ethanesulfonate - ICP-AES inductively coupled plasma atomic emission spectrometry - SDS-PAGE sodium dodecylsulfate polyacrylamide gel electrophoresis - EPR electron paramagnetic resonance spectrometry     

Rhodobacter capsulatus strain BK5 possesses a membrane bound respiratory nitrate reductase rather than the periplasmic enzyme found in other strains

Rhodobacter capsulatus strain BK5 possesses a membrane bound respiratory nitrate reductase rather than the periplasmic enzyme found in other strains. The enzyme in strain BK5 is shown to be both functionally and structurally related to the nitrate reductase of Paracoccus denitrificans and Escherichia coli.Abbreviation TMAO trimethylamine-N-oxide     

辣椒素引起脊髓P物质释放及其对血压的影响

为进一步研究脊髓 P 物质(SP)在调节心血管活动中的作用,在大鼠脊髓蛛网膜下腔注射(ith)辣淑素(cap),以刺激脊髓 SP 能神经末梢释放 SP,结果引起血浆去甲肾上腺素(NA)和肾上腺素(AD)含量增高,及具有剂量依赖性的动脉血压上升,心率升高。ith 具有高度特异性的 SP 受体拮抗剂或 SP 抗血清均可阻断 cap 引起的升压效应,免疫组化测定也观察到注入的cap 剂量越大,脊髓胸段 SP 样免疫阳性反应物的致密度越低,这些观察结果支持 cap 可以引起脊髓内 SP 的释放的说法。在第一颈段(C_1)横断脊髓后 ith cap 所引起的升压效应与完整动物 ith cap 的升压效应无显著差异。以上结果提示脊髓 SP 能神经末梢释放的 SP 可以通过交感肾上腺髓质系统引起心血管兴奋效应,SP 可能是引起交感节前神经元兴奋的神经递质。     

大鼠缰核与下丘脑外侧区在调节心血管活动方面的机能联系

电刺激大鼠下丘脑外侧区（LH）,动脉压明显升高,心率加快,在刺激电极同侧缰核（Hb)内微量注射盐酸利多卡因、电刺激LH引起的升压反应可被阻断38.9%,心率增快反应可被阻断44.4%,双侧Hb内微量注射盐酸利多卡因,电刺激LH引起的升压反应可被阻断40.7%,心率增快反应可被阻断41.2% ,单侧或双侧Hb内微量注射人工脑脊液均不能阻断电刺激LH引起的心血管反应。电刺激大鼠Hb,动脉压明显升高,心率无明显改变,在刺激电极同侧LH内微量注射盐酸利多卡因,电刺激Hb引起的升压反应可被阻断63.2%,双侧LH内微量注射盐酸利多卡因,电刺激Hb引起的升压反应可被阻断62.6%,单侧或双侧LH内微量注射人工脑脊液均不能阻断电刺激Hb引起的心血管反应。本实验提示Hb与LH在调节心血管活动方面有协同作用。     

抗马拉硫磷淡色库蚊不同基因型的自然内禀增长率及其对抗性演化的影响

本文涉及淡色库蚊(Culex pipiens pallens)抗马拉硫磷纯合子(RR)、杂合子(RS)和敏感纯合子(SS)的自然内禀增长率及其对马拉硫磷抗性演化的影响。RR、RS和SS的内禀增长率分别为0.1118、0.1171和0.1339。RR和RS基因型在无杀虫剂时呈现出繁殖不利性,RR和RS的相对适合度分别是SS的0.65和0.68。 影响淡色库蚊对马拉硫磷进化的某些因子在计算机上进行了模拟。模拟的因子包括R等位基因的起始频率(P_o)、所用马拉硫磷的剂量和迁入率(m)。模拟结果表明(I)不用药时R等位基因衰减是由于RR和RS基因型的繁殖不利性;(2)在起始种群N_o=200,P_o=0.1,使用杀死全部SS和RS的剂量(8ppm)处理,使R等位基因为有效隐性,并且m≥0.15时可阻止马拉硫磷抗性的发生。     

Relationships of pollen size,pistil length and pollen tube growth rates in Rhododendron and their influence on hybridization

Summary Pollen size and pistil length data have been collected for 93 species of Rhododendron (Ericaceae) belonging to a number of different subgeneric taxa. For a sample of eight species in section Vireya, pollen tube growth in the style after selfor interspecific pollination has been quantified. Pollen volume and the time taken for pollen tubes to reach the ovary were both related to pistil length. Pollen-tube growth rates were generally greater for species with longer pistils and larger pollen. Increasing temperature increased the rate of pollen-tube growth. There was no detectable effect of pollen tube density on tube growth rate in the style. After interspecific pollinations tube growth rates in foreign styles could be faster or slower than in self styles. A semisterile individual with two viable pollen grains per tetrad and a plant grafted as scion to a longer-styled stock both showed more rapid pollen-tube growth than expected on the basis of pistil size. Data collected for 26 species in section Vireya showed that where extreme disparity of pollen/pistil size causes failure of interspecific crosses, one or more bridging species with intermediate pollen/pistil size can generally be selected.     

Thermoregulatory adjustments during continuous heat exposure

Body temperature regulation was studied in 6 male subjects during an acclimation procedure involving uninterrupted heat exposure for 5 successive days and nights in a hot dry environment (ambient temperature = 35 degrees C, dew-point temperature = 7 degrees C; air velocity = 0.2 m.s-1). Data were obtained at rest and during exercise (relative mechanical workload = 35% VO2max). At rest, hourly measurements were made of oesophageal and 4 local skin temperatures, to allow the calculation of mean skin temperature, and of body motility and heart rate. During the working periods these measurements were made at 5 min intervals. Hourly whole-body weight loss was measured at rest on a sensitive platform scale while in the working condition just before starting and immediately after completing the bicycle exercise. The results show that, in both exercise and at rest, the successive heat exposures increased the sweat gland output during the first 3 days. Afterwards, sweat rate decreased without any corresponding change in body temperature. For the fixed workload, the sweat rate decline was associated with a decrease in circulatory strain. Adjustments in both sweating and circulatory mechanisms occur in the first 3 days of continuous heat exposure. The overall sweat rate decline could involve a redistribution of the regional sweating rates which enhances the sweat gland activities of skin areas with maximal evaporative efficiencies.     

The arthropod gap junction and pseudo-gap junction: Isolation and preliminary biochemical analysis

Summary The hepatopancreas of the crayfish, Procambarus clarkii, contains an unusual abundance of gap junctions, suggesting that this tissue might provide an ideal source from which to isolate the arthropod-type of gap junction. A membrane fraction obtained by subcellular fractionation of this organ contained smooth septate junctions, zonulae adhaerentes, gap junctions and pentalaminar membrane structures (pseudo-gap junctions) as determined by electron microscopy. A further enrichment of plasma membranes and gap junctions was achieved by the use of linear sucrose gradients and extraction with 5 mM NaOH. The enrichment of gap junctions correlated with the enrichment of a 31 Kd protein band on polyacrylamide gels. Extraction with 20 mM NaOH or 0.5% (w/v) Sarkosyl NL97 resulted in the disruption and/or solubilization of gap junctions. Negative staining revealed a uniform population of 9.6 nm diameter subunits within the gap junctions with an apparent sixfold symmetry. Using antisera to the major gap junctional protein of rat liver (32 Kd) and to the lens membrane protein (MP 26), we failed to detect any homologous antigenic components in the arthropod material by immunoblotting-enriched gap junction fractions or by immunofluorescence on tissue sections. The enrichment of another membrane structure (pseudo-gap junctions), closely resembling a gap junction, correlated with the enrichment of two protein bands, 17 and 16Kd, on polyacrylamide gels. These structures appeared to have originated from intracellular myelin-like figures in phagolysosomal structures. They could be distinguished from gap junctions on the basis of their thickness, detergent-alkali insolubility, and lack of association with other plasma membrane structures, such as the septate junction. Pseudo-gap junctions may be related to a class of pentalaminar contacts among membranes involved in intracellular fusion in many eukaryotic cell types. We conclude that pseudo-gap junctions and gap junctions are different cellular structures, and that gap junctions from this arthropod tissue are uniquely different from mammalian gap junctions of rat liver in their detergentalkali solubility, equilibrium density on sucrose gradients, and protein content (antigenic properties).     

肾神经在扩张心房时对尿量和尿钠排出的作用

单侧肾去神经的麻醉狗,用乳胶小囊扩张肺静脉-心房连接部,观察到神经完好肾的尿流量与排钠量均显著增加(P<0.01);去神经肾的尿流量仍显著增加(P<0 01),但排钠量无明显变化(P>0.05);两侧肾的肾小球滤过率(GFR)及肾血浆流量(RPF)均保持稳定;神经完好肾的静脉血浆肾素活性(PRA)及血管紧张素Ⅱ水平(PAⅡ)均明显降低,PAⅡ降低的幅度与尿流量增加的幅度无相关(r=-0.2975,P>0.05);与排钠量增加的幅度也无相关(r=-0.2359,P>0.05);去神经肾的PRA和PAⅡ都没有显著变化。说明在刺激心房感受器引起的利尿与尿钠排泄的反应中,肾神经主要促进肾对尿钠的排出。肾神经的这种作用既不是通过改变GFR和RPF,也不是抑制肾素的释放,而可能是由于直接影响肾小管对钠的重吸收。