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101.
目的:探讨兔在体左室肥厚心肌单相动作电位跨室壁的不均一性变化。方法:以腹主动脉缩窄术制备家兔高血压左室肥厚模型,并设假手术组(仅游离腹主动脉未缩窄)作为对照。采用自制复合式电极在兔左心室前壁同步记录心内膜、心肌中层、心外膜在体3层心肌单相动作电位(MAP),比较两组间跨室壁复极离散度(TDR)等各项参数的差异。结果:腹主动脉缩窄组平均动脉压、全心重量及其与体重比率、左心室游离壁厚度均大于假手术组。缩窄组3层心肌MAPD100[内膜:(191±19)ms;中层:(244±24)ms;外膜:(196±15)ms]均长于对照组[内膜:(170±18)ms ;中层:(172±15)ms;外膜:(168±16)ms,P<0.01],以中层心肌MAPD100延长最为明显,缩窄组TDR(65±10)ms较对照组(4±3)ms明显增大(P<0.01)。结论:兔在体左室肥厚心肌跨室壁电不均一性明显增大,可能是肥厚心肌心律失常发生增多的原因之一。 相似文献
102.
T. Rodriguez N. Aptsiauri R. Méndez P. Jimenez F. Ruiz-Cabello & F. Garrido 《Tissue antigens》2007,69(S1):259-263
103.
104.
Stroke in rodents is associated with increased neurogenesis and the migration of newborn neurons to sites of brain ischemia, where they may participate in repair and recovery. To determine if neurogenesis following stroke yields functional new neurons, we labeled neuronal precursors in the mouse subventricular zone (SVZ) with a lentivirus-green fluorescent protein vector, produced stroke by occluding the middle cerebral artery, and detected newborn neurons 8 weeks later by fluorescence microscopy. Patch-clamp studies on fluorescent neurons in the cortical region surrounding infarction showed tetrodotoxin-sensitive Na+ action potentials and spontaneous excitatory post-synaptic currents, suggesting that ischemia led to functional neurogenesis with synaptic integration. These findings support the hypothesis that enhancing endogenous neurogenesis after stroke might have therapeutic benefit. 相似文献
105.
106.
M. B. Dutia Alexander R. Johnston 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1998,118(2):148-154
The postnatal maturation of medial vestibular nucleus (MVN) neurones was examined in slices of the dorsal brainstem prepared
from balb/c mice at specific stages during the first postnatal month. Using spike-shape averaging to analyse the intracellularly recorded
action potentials and after-hyperpolarisations (AHPs) in each cell, all the MVN neurones recorded in the young adult (postnatal
day 30; P30) mouse were shown to have either a single deep AHP (type A cells), or an early fast and a delayed slow AHP (type
B cells). The relative proportions of the two subtypes were similar to those in the young adult rat. At P5, all the MVN cells
recorded showed immature forms of either the type A or the type B action potential shape. Immature type A cells had broad
spontaneous spikes, and the characteristic single AHP was small in amplitude. Immature type B cells had somewhat narrower
spontaneous spikes that were followed by a delayed, apamin-sensitive AHP. The delayed AHP was separated from the repolarisation
phase of the spike by a period of isopotentiality. Over the period P10–P15, the mean resting potentials of the MVN cells became
more negative, their action potential fall-times became shorter, the single AHP in type A cells became deeper, and the early
fast AHP appeared in type B cells. Until P15 cells of varying degrees of electrophysiological maturity were found in the MVN
but by P30 all MVN cells recorded were typical adult type A or type B cells. Exposure to the selective blocker of SK-type
Ca-activated K channels, apamin (0.3 μM), induced depolarising plateaux and burst firing in immature type B cells at rest.
The duration of the apamin-induced bursts and the spike frequency during the bursts were reduced but not abolished after blockade
of Ca channels in Ca-free artificial cerebrospinal fluid containing Cd2+. By contrast, in mature type B cells at rest apamin selectively abolished the delayed slow AHP but did not induce bursting
activity. Apamin had no effect on the action potential shape of immature type A cells. These data show that the apamin-sensitive
I
AHP is one of the first ionic conductances to appear in type B cells, and that it plays an important role in regulating the intrinsic
rhythmicity and excitability of these cells.
Received: 19 November 1996 / Accepted: 30 June 1997 相似文献
107.
June Mason Hans-Ulrich Gutsche Leon Moore Roland Müller-Suur 《Pflügers Archiv : European journal of physiology》1979,379(1):11-18
Experiments were conducted to establish whether diminished solute reabsorption in the loop of Henle during acute renal failure could explain the loss of urinary concentration and participate in generating a tubuloglomerular feedback-mediated reduction in filtration rate. The electrolyte content of the fluid in the ascending limb of the loop of Henle was determined in situ by monitoring its electrical conductivity after propulsion into the distal tubule with a sudden burst perfusion. The value of the minimum electrolyte concentration decreased exponentially with increasing equilibration time, reaching a steady-state value equivalent to 27±9 mM NaCl in normal kidneys, 34±15 mM in mercuric chloride kidneys and 53±22 mM following ischaemia. A mathematical model was derived to describe the process of sodium chloride dilution from which it was possible to calculate both the permeability and transport velocity of the cortical thick ascending limb. In the normal kidney, the transport velocity was calculated to be 4.65±0.92 ·10–5 cm/s, a value not significantly different from that of the mercuric chloride or ischaemic kidneys, and the estimated permeability was 1.13±0.52·10–5 cm/s, not different from that of the mercuric chloride kidneys but significantly lower than that calculated for the ischaemic kidneys. It is concluded that for the more severely damaged ischaemic model, the loss of urinary concentrating ability was accompanied by a reduction in diluting ability of the ascending limb of the short loop of Henle, which appears to be due, at least in part, to an elevation of the passive permeability to sodium chloride in this segment. 相似文献
108.
人格特征与防御方式的相关研究 总被引:7,自引:2,他引:7
目的 :尝试用防御机制解释EPQ各维度的特征。方法 :采用EPQ人格问卷、DSQ防御方式问卷、16PF中的G量表对 2 2 0例成人进行测试。结果 :本样本中EPQ各维度与成熟防御方式均无显著相关 (P >0 .0 5 ) ,N维度和P维度均与不成熟防御方式、中间型防御方式有显著正相关 (P <0 .0 0 1)。结论 :本研究显示 ,可以用防御机制解释EPQ各维度的某些特征。 相似文献
109.
L-Type Ca2+ current (I
Ca,L) elicited during the action potential (AP) of guinea-pig ventricular myocytes exhibits an early and a late component. The
whole-cell patch-clamp technique was used to characterize the process regulating the late I
Ca,L component and to assess its contribution to excitation-contraction coupling. A stepwise decrease in repolarization rate of
AP-like voltage-clamp pulses led to an exponential increase in Ca2+ charge carried by I
Ca,L. This saturation behaviour was significantly reduced or absent when Ba2+ or monovalent cations were used as charge carriers, which suggests that the late component of I
Ca,L is controlled mainly by Ca2+-dependent processes. Simultaneously recording I
Ca,L and zero-load shortening or the internal Ca2+ concentration (fura-2) revealed that Ca2+ carried by the late component of I
Ca,L markedly contributes to the Ca2+ content of the sarcoplasmic reticulum (SR). Reducing the charge transfer by late I
Ca,L during a series of AP-like conditioning clamp pulses by 48% reduced the shortening amplitude during a subsequent test stimulation
by 56%. This relationship was absent during long rectangular depolarizing conditioning clamps, during which Na+/Ca2+ exchange increased its influence on SR Ca2+ loading. The late component of I
Ca,L developed only a minor direct influence on the simultaneous cell shortening. Thus, the main contribution of the late I
Ca,L component is to supply Ca2+ for SR loading.
Received: 5 November 1997 / Received after revision: 12 June 1998 / Accepted: 15 June 1998 相似文献
110.
齿龈内阿米巴的致病作用与致病机制的研究 总被引:1,自引:0,他引:1
在注射免疫抑制剂 1周后的大白鼠龈缘涂抹齿龈内阿米巴 (Emtamoebagingivalis ,E .g .) ,5天后 ,牙龈组织出现溃疡、牙周脓肿形成、脓液查见活E .g .、牙槽骨吸收等牙周炎病症。电镜术与生化分析发现 :E .g .伪足活跃、有丰富的溶酶体 ,所含水解酶与ACP显著较健康组高 (P <0 0 1) ,可使牙周组织溶解与受损。SOD较健康组显著性低 (P <0 0 1) ,MDA显著性增高 (P <0 0 1) ,说明E .g .感染产生较多氧自由基可使细胞膜受损 ,加上口腔共生菌的协同作用使免疫力低下的宿主发生牙周炎。 相似文献