Effects of the Na+/H+-exchange inhibitor Hoe 642 on intracellular pH, calcium and sodium in isolated rat ventricular myocytes

The inhibitors of the Na+/H+-exchange (NHE1) system Hoe 694 and Hoe 642 possess cardioprotective effects in ischaemia/reperfusion. It is assumed that these effects are due to the prevention of intracellular sodium (Nai) and calcium (Cai) overload. The purpose of the present study was to investigate the effects of Hoe 642 on intracellular pH, Na+ and Ca2+ (pHi, Nai and Cai) in isolated rat ventricular myocytes under anoxic conditions or in cells in which oxidative phosphorylation had been inhibited by 1.5 mmol/l cyanide. In cells which were dually loaded with the fluorescent dyes 2, 7-biscarboxyethyl-5,6-carboxyfluorescein (BCECF) and Fura-2, anoxia caused acidification of the cells (from pHi 7.2 to pHi 6.8) and an increase in Cai from about 50 nmol/l to about 1 micromol/l. The decrease in pHi began before the cells underwent hypoxic (rigor) contracture, whereas Cai only began to rise after rigor shortening had taken place. After reoxygenation, pHi returned to its control value and Cai oscillated and then declined to resting levels. It was during this phase that the cells rounded up (hypercontracture). When 10 micromol/l Hoe 642 was present from the beginning of the experiment, pHi and Cai were not significantly different from control experiments. At reoxygenation, pHi did not recover, but Cai oscillated and returned to its resting level. To monitor Nai, the cells were loaded with the dye SBFI. After adding 1.5 mmol/l cyanide or 100 micromol/l ouabain, Nai increased from the initial 8 mmol/l to approximately 16 mmol/l. Hoe 642 or Hoe 694 (10 micromol/l) did not prevent the increase in Nai. In contrast, the blocker of the persistent Na+ current R56865 (10 micromol/l) attenuated the CN--induced rise in Nai. The substance ethylisopropylamiloride was not used because it augmented considerably the intensity of the 380 nm wavelength of the cell's autofluorescence. In conclusion, the specific NHE1 inhibitor Hoe 642 did not attenuate anoxia-induced Cai overload, nor CN--induced Nai and Cai overload. Hoe 642 prevented the recovery of pHi from anoxic acidification. This low pHi maintained after reoxygenation may be cardioprotective. Other possible mechanisms of NHE1 inhibitors, such as prevention of Ca2+ overload in mitochondria, cannot be ruled out. The increase in Nai during anoxia is possibly due to an influx of Na+ via persistent Na+ channels.     

Monensin-induced reversal of positive force-frequency relationship in cardiac muscle: role of intracellular sodium in rest-dependent potentiation of contraction

We have investigated the role of a rest-dependent inotropic factor in determining species-related differences in cardiac force-frequency relationships (FFR). Isolated rat, rabbit or guinea-pig papillary muscles, as well as guinea-pig ventricular myocytes were superfused with 1.8 mM Ca2+ Tyrode. In rat muscles, isometric force amplitude decreased, while in rabbit or guinea-pig muscles force increased with frequency (0.02-1 Hz). Paired-pulse pacing potentiated contraction markedly at all frequencies in rabbit muscles, but not at low frequencies in rat muscles. We tested the hypothesis that high intracellular Na+ levels (Nai) are responsible for negative FFR. The ionophore monensin increased Nai, reversed the FFR of rabbit and guinea-pig muscles from positive to negative, by increasing force mostly at low frequencies, and decreased the paired-pulse potentiation of contraction at low frequencies. Monensin added during rest also reversed rest-induced decay. In isolated myocytes, monensin had qualitatively similar effects on cell shortening as well as on Cai transients. Monensin also decreased the action potential duration (APD) but did not change the pattern of its variation with frequency. Cells intracellularly dialyzed with 20 mM Na+ via a patch pipette also showed rest potentiation of the Cai transients, in contrast to cells dialyzed with 10 mM Na+, which showed rest decay of the transients. APD was also shorter in myocytes dialyzed with 20 mM Na+ than in those dialyzed with lower Na+. The results indicate that in the presence of high Nai, sarcoplasmic reticular Ca2+ load is increased during diastole, possibly via reverse-mode Na+/Ca2+ exchange, and therefore that Nai is an important factor determining the FFR. In addition, the data suggest that short APDs in preparations showing negative FFR may be partly a consequence of increased Nai.     

Changes in thyroid state affect pHi and Nai+ homeostasis in rat ventricular myocytes

We have tested the hypothesis that thyroid state may influence both the flow of cellular Ca2+ and the myofilament response to Ca2+ by effects on intracellular pH (pHi) and Na+ (Nai+). Single cardiac myocytes isolated from hypothyroid, euthyroid and hyperthyroid animals were loaded with fura-2/AM (Cai2+ probe), BCECF/AM (pHi probe) or SBFI/AM (Nai+ probe). Compared with hypothyroid animals, myocytes isolated from hyperthyroid rat hearts demonstrated a significant: (1) increase in extent of shortening; (2) decrease in the time to peak contraction; (3) increase in the peak amplitude of the fura-2 fluorescence ratio; (4) decrease in pHi (DeltapHi=0. 19+/-0.05); and (5) increase in Nai+ (DeltaNai+=2.88+/-0.55 mM). We have also compared pHi in Langendorff perfused hypo- and hyperthyroid rat hearts using NMR. We have found that hyperthyroid hearts are 0.15+/-0.03 pH units more acidic than hypothyroid hearts. Analysis of mRNA levels demonstrated that hyperthyroidism increased expression of both the Na+/Ca2+ exchanger and Na+/H+ antiporter, and decreased expression of Na+ channel mRNAs. These changes appear partially responsible for the observed changes in Nai+ and pHi. Our results provide the first evidence that changes in cardiac contractility associated with altered thyroid state not only involve effects on Ca2+, but may also involve changes in the response of the myofilaments to Cai2+mediated by altered pHi and Nai+.     

Ischemic preconditioning: effects on pH, Na and Ca in newborn rabbit hearts during Ischemia/Reperfusion

In adult hearts, ischemic preconditioning (PC) has been shown to decrease ischemia-induced changes in intracellular pH (pHi) and [Ca] ([Ca]i) and decrease associated injury. These results are consistent with the interpretation that PC decreases the stimulus for Na uptake via Na/H exchange, thereby decreasing intracellular Na (Nai) accumulation, and thus decreasing the change in force driving Na/Ca exchange, which otherwise contributes to ischemia-induced increases in [Ca]i. Given documented age-related differences in myocardial responses to ischemia, we tested the hypothesis that in newborn hearts, PC will diminish intracellular [H], Nai, and [Ca]i during ischemia/reperfusion. NMR was used to measure pHi, Nai, [Ca]i, ATP, and PCr in isolated newborn (4-7 days) rabbit hearts Langendorff-perfused with Krebs-Henseleit solution equilibrated with 95% O2/5% CO2 at 36+/-1 degrees C. Control hearts were perfused 30 min before initiating 40 min global ischemia followed by 40 min reperfusion. PC hearts were treated the same except four 5-min intervals of ischemia each followed by 10 min of perfusion which preceded global ischemia. At end ischemia, pHi was higher in PC than control hearts (6.31+/-0.03 v 5.83+/-0.05; P<0.05). Similarly, PC diminished Nai-accumulation during ischemia and reperfusion (P<0.05). Control Nai rose from 16.2+/-2.6 to 108.8+/-10.3 (mEq/kg dry weight) and recovered to 55.2+/-10.1 and the corresponding values for PC hearts were 25.6+/-6.2, 70.0+/-7.9 and 21.9+/-5.2. PC also improved [Ca]i recovery during reperfusion (P<0.05). Control [Ca]i rose from 418+/-43 to 1100+/-78 (nm/l) and recovered to 773+/-63, whereas in PC hearts the values were 382+/-40, 852+/-136 and 371+/-45, respectively. In addition, PC decreased coronary resistance during reperfusion (P<0.05) as reflected by lower perfusion pressures under constant flow conditions (65.9+/-1.5 v 56. 1+/-4.1 mmHg at end of reperfusion). Finally, PC improved recovery of left-ventricular developed pressure (LVDP-43.8+/-12.0 v 17.2+/-3. 0% of control; P<0.05) and diminished CK release (607+/-245 v 2432+/-639 IU/g dry weight; P<0.05) during reperfusion. The results are consistent with the hypothesis.     

Relationship of red blood cell ion transport alterations and serum lipid abnormalities in Lyon genetically hypertensive rats

Alterations of Na+ and K+ transport in erythrocytes of hypertensive humans or animals are often associated with abnormal lipid metabolism. The aim of the present study was to investigate red blood cell ion transport in Lyon inbred strains selected from Sprague-Dawley rats for different blood pressure levels. Lyon strains are characterized by important metabolic changes, including plasma lipid abnormalities. Serum triglycerides, cholesterol, and uric acid as well as red blood cell Na+ and K+ (Rb+) transport mediated by Na(+)-K+ pump or Na(+)-K+ cotransport and cation leaks were studied in hypertensive (LH), normotensive (LN), and low blood pressure (LL) Lyon rats aged 12 weeks. Increased erythrocyte Na+ content (Nai+) and higher levels of serum triglycerides, cholesterol, and uric acid were demonstrated in LH rats compared with LN animals. Nevertheless, at this age serum triglycerides and erythrocyte Nai+ of LL rats were even higher than those of LH animals. There were no significant differences between Lyon strains in either Na(+)-K+ pump activity or bumetanide-resistant (BR) cation leaks. The activity of bumetanide-sensitive (BS) Na(+)-K+ cotransport mediating inward Na+ movement was highest in LL rats and lowest in LH animals. In Lyon rats, Nai+ was positively related to serum triglycerides, whereas blood pressure correlated positively with BR Na+ leak and negatively with BS net Na+ uptake. A similar association of erythrocyte Nai+ with serum triglycerides was also observed in Prague hereditary hypertriglyceridemic rats (HTG) that were selected from Wistar rats for high plasma triglycerides. The major difference of the two forms of genetic hypertension associated with abnormal lipid metabolism was in BS net Na+ uptake, which was enhanced in HTG but reduced in LH rats. This was probably due to differences in plasma cholesterol, which was elevated in LH but not in HTG animals. Our study in Lyon rats confirmed the positive association of blood pressure with Na+ leak as a characteristic feature of genetic hypertension.     

Na+-Ca2+ exchange is affected by membrane potential in cardiac sarcolemmal vesicles

The effect of membrane potential on the Na+-Ca2+ exchange activity of isolated sarcolemmal vesicles from dog ventricles is examined. Na+-Ca2+ exchange is monitored as Nai+-dependent Ca2+ uptake as described by Reeves and Sutko ((1979) Proc. Natl. Acad. Sci. U. S. A. 76,590-594). Membrane potential is controlled by varying internal and external K+ in the presence of valinomycin. Inside-positive potentials stimulate Nai+-dependent Ca2+ influx. This stimulation is independent of Ca2+ concentration. The results indicate that Na+-Ca2+ exchange by itself can generate a substantial potential (approximately -60mV) in the sarcolemmal vesicles. The data are consistent with an electrogenic Na+-Ca2+ exchange mechanism in which three or more Na+ are exchanged for one Ca2+. This electrogenic exchange may have important implications in the control of myocardial tension development.     

广西平南六浊岭冶铁遗址出土冶金遗物初步研究

广西贵港市平南县六陈镇六浊岭遗址是目前贵港地区冶铁遗址群中唯一一处经科学发掘并报告的冶炼遗址,共清理出了13座炼炉,出土了大量炉渣、矿石、木炭、鼓风管及炉壁等冶金遗物。对出土木炭进行碳十四测年分析,结合出土陶瓷器类型学分析可知,六浊岭遗址为一处晋唐时期的冶炼遗址。采用扫描电子显微镜能谱仪（SEM-EDS）成分分析及金相显微镜观察等科学分析方法对遗址出土的炉渣、铁块及矿石等冶金遗物进行科学分析,结果表明,平南六浊岭遗址为一处块炼铁遗址。     

机车车辆车轮车床数控改造方案分析

针对金川集团公司铁路运输分公司现有触点式仿形车轮车床，存在加工精度低，故障率高的问题。提出进行数控改造的设计方案，并对改造方案进行了具体的分析。     

Na/K pump current in guinea pig cardiac myocytes and the effect of Na leak

INTRODUCTION: Steady-state Na/K pump current (Ip) in adult guinea pig ventricular myocytes was studied to determine the effect on the Na/K pump of transmembrane Na leak, membrane potential, and pipette Na concentration. METHODS AND RESULTS: Using conventional whole cell, patch clamp techniques, Ip was identified as either Ko-sensitive or ouabain-sensitive current when most other membrane currents were inhibited. Control experiments showed that there were no Ko-sensitive currents other than Ip under the conditions of our experiments. Ip was found to be similar to that reported by others being voltage dependent between -130 and 0 mV and having a half maximal activation by Nai of 28 mM. Ouabain sensitivity was also measured, and it was found that there were two binding sites with the high affinity site comprising 5% to 10% of the total and having an apparent affinity 1000-fold higher than the low affinity site. Apparent affinity of both sites was shifted about 10-fold (higher affinity) by increasing Nai from 10 to 85 mM. When internally perfused with 0 Na solution, Na leak through the membrane was found to be linearly related to Na/K pump activity. In contrast to prior suggestions, Ip was not correlated with series resistance when there was a large transmembrane Na gradient. CONCLUSION: These data suggest that, under conditions of high transmembrane Na gradient, Na leak through the membrane plays a significant role in determining Na/K pump activity.     

Correction to Schulz et al. (2005).

Reports an error in the original article by Kurt P. Schulz, Cheuk Y. Tang, Jin Fan, David J. Marks, Angeles M. Cheung, Jeffrey H. Newcorn, and Jeffrey M. Halperin ((Neuropsychology, 2005, Vol. 19, No. 3, pp. 390-402). Some side headings in Tables 2 and 3 were incorrect, and the corrected tables appear here. (The following abstract of this article originally appeared in record 2005-05103-013). "The authors examined inhibitory control processes in 8 adolescents diagnosed with attention-deficit/ hyperactivity disorder (ADHD) during childhood and in 8 adolescent control participants using functional MRI with the Stimulus and Response Conflict Tasks (K. W. Nassauer & J. M. Halperin, 2003). No group differences in performance were evident on measures of interference control and/or response competition created by location and direction stimuli. However, the ADHD group demonstrated significantly greater activation of the left ventrolateral prefrontal cortex during interference control as well as greater activation of the left anterior cingulate cortex, right ventrolateral prefrontal cortex, and left basal ganglia during the dual task of interference control and response competition. The magnitude of the prefrontal and basal ganglia activation was positively correlated with severity of ADHD. Response competition alone did not yield group differences in activation." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

安泰1250m~3高炉渣处理系统设计特点

详细介绍安泰1 250 m3高炉渣处理系统的设计参数、工艺布置、工艺流程特点、主要设施配置以及设计存在的不足。设计中吸收平流法、嘉恒法、INBA法渣处理工艺的优点,对渣处理工艺作出合理布置,满足了高炉生产要求。     

Clinical biochemistry, haematology and body weight in piglets

Reference ranges for clinical biochemical parameters commonly investigated in pigs were determined in one- (day 1), 21- and 35-day old piglets. The mean and standard deviation were also estimated for body weight, and haematological and clinical biochemical parameters at these ages. The piglets were divided into 2 investigation groups according to whether they had a haemoglobin concentration < or = 80 g/l ("anaemic group") or > 80 g/l ("normal group") on days 14, 21 and 28. The "anaemic group" was compared to the "normal group" on days 21 and 35. Many of the clinical biochemical parameters varied according to age. Some of the enzymes had high average values and wide reference ranges in piglets, especially on day 1, compared to the reference ranges for sows given in the literature. The reference ranges for some of the metabolic parameters were broader on day 1 than later in the preweaning period. The reference ranges for albumin, total iron-binding capacity and serum iron were, however, lower and more narrow on day 1. On days 21 and 35, relatively high values for phosphorus must be considered "normal" compared to the figures given in the literature for adult pigs. The other minerals seemed to be quite unaffected of age, but some were affected by anaemia. The anaemic piglets had lower average serum iron but higher total iron-binding capacity than the "normal" piglets on days 21 and 35. However, variation between piglets gave wide reference ranges, indicating that these parameters will only have limited usefulness in detecting iron deficiency anaemia in piglets. The electrolytes seemed also to be affected by the existence of anaemia. The body weight and leukocyte counts were significantly lower in the "anaemic group" than the "normal group" on day 35, while the greatest differences in clinical biochemical parameters between the groups were found on day 21, when the piglets in the "anaemic group" were most severely anaemic. Although these piglets suffered from severe iron-deficiency anaemia, only a few clinical biochemical parameters were affected, and the differences between groups were mostly small.     

Interactions among operator variables, system dynamics, and task-induced stress.

The relative efficiency of several machines is studied under conditions of operator stress. "Forty-eight naval enlisted men served as Ss in the three experiments—16 Ss per experiment." In each of the 3 experiments, the Ss were divided into 2 groups of 8: an experimental and a control group. 3 systems were employed: acceleration control, acceleration aided control, and position control. In Experiment I, one group used the acceleration; the other used the acceleration aided. In Experiment II, one group used the acceleration and the other the acceleration aided. In Experiment III, one group used position control and the other the acceleration. Stress was introduced in all cases as the trials progressed. "The better systems retained their advantage under stress… . Thus, within the confines of the present studies the "engineering" variable of system dynamics proved to be ascendent over the "psychological" variables of selection and training in determining relative performance under stress." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Psychopathy, threat, and polygraph test accuracy.

The accuracy of the control question polygraph test with psychopaths was evaluated within a realistically threatening context. Subjects were 24 psychopathic and 24 nonpsychopathic male prison inmates. Within each diagnostic group, equal numbers of "guilty" and "innocent" subjects were tested by experienced professional polygraphers regarding their involvement in a mock theft by using standard control question procedures. A group contingency threat was devised in which subjects believed that their personal performance could decide benefits or penalties for the sample as a whole. Guilty psychopaths were detected just as easily as guilty nonpsychopaths, and the majority of guilty subjects (87%, excluding inconclusives) were correctly identified. However, innocent subjects were identified with only 56% accuracy, and an analysis of false positive errors suggested that the subjective impact of the threat was a critical factor in these outcomes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Yielding, authoritarianism, and authoritarian ideology regarding groups.

This investigation was prompted by Asch's (1952) discussion of the personal and social significance of yielding to group pressure. For the person, yielding requires the inhibition of overt and perhaps implicit responses to objective situational requirements. For the group, malignant processes may arise and develop, unchecked by those members in whom goals of personal security predominate over group goals. In the present study, the view was taken that both meanings of yielding are assigned positive value in two separate ideologies concerning the group-individual relation. One of these is termed "conformity" and the other is "rugged individualism." In the study, group pressure was simulated by announcing bogus group judgments to small groups of Ss whose apparent task was to match one of three lines of variable length with a standard line. Questionnaires were used to measure variables, which were: the ideology of conformity (IC), the ideology of rugged individualism (RI), ethnocentrism (E), and authoritarianism (F). The questionnaires were administered to 91 college students, both day school and evening. It was found that the correlation with the F scale was .48 (P     

"Training group members to set session agendas: Effects on in-session behavior and member outcome": Correction to Kivlighan, Jauquet, Hardie, Francis, and Hershberger.

Reports an error in "Training group members to set session agendas: Effects on in-session behavior and member outcome" by Dennis M. Kivlighan, Carol A. Jauquet, Anne W. Hardie, Anna Maria Francis and Bernard Hershberger (Journal of Counseling Psychology, 1993[Apr], Vol 40[2], 182-187). In Table 4 (p. 186) the values for the means and standard deviations in the second, third, and fourth rows of the "Agenda setting" column were transposed with those in the "No contact" column. The corrected table is presented in this erratum. (The following abstract of the original article appeared in record 1993-26598-001.) Addressed I. D. Yalom's (1983) hypothesis that group members who set session agendas would participate more effectively in group sessions and have enhanced outcomes. The independent variable, agenda, was manipulated by assigning the 24 members of established personal growth groups to 1 of 3 conditions: (1) training in agenda setting, (2) stabilizing interviews, and (3) no-contact control. Group members filled out pre- and posttest measures of enactments of intimate behaviors and attitudes toward these enactments. They also filled out self- and other ratings of in-group enactments of intimate behaviors, and group leaders rated group members' intimate behavior at the end of each group session. Group members who set here-and-now session agendas enacted more in-group intimate behaviors and had better outcomes. Implications of these results and suggestions for group counseling are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social desirability and responses to items from three MMPI scales: D, Sc, and K.

For random samples of 25 D and 32 Sc items, and for 29 of the 30 K items, ratings of social desirability were correlated with the probabilities that the items would be endorsed when the MMPI was used as a personality test (based on proportion of a college student sample actually endorsing each item). The correlations were .82 and .89 for the D and Sc items respectively. For the K-scale items, correlations of social desirability were computed with endorsement probabilities from a "typical college sample" (r = .50), and "Average-K" group (r = .38), and a "high-K" group (r = .66). "The results were interpreted as demonstrating the validity of K as a measure of the set to respond to items in terms of their social desirability." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cultural similarities and differences in group work: Pilot study of a U.S.–Chinese group comparison.

This pilot study representing collaborative cross-cultural research was conducted to compare cross-cultural similarities and differences between 2 comparable task groups by using the 8-step learning through discussion (LTD; W. F. Hill, 1969) method. One LTD group was conducted in the United States with U.S. members; the other LTD group was conducted in China with Chinese members. The same scholarly article on career needs of Chinese middle school students provided the discussion input (M. H. France, Y. Jin, K. Huang, F. Si, & W. Zhang, 1991). Videotapes of each group were made for comparative review by the researchers, providing for analysis of similarities and differences in verbal interaction, nonverbal interaction, leader role, and content themes. Implications of the results and suggestions for U.S. group leaders in working with Chinese task groups are provided. (PsycINFO Database Record (c) 2010 APA, all rights reserved)