心钠素免疫反应在豚鼠耳蜗中的整体分布

目的 :研究豚鼠耳蜗中心钠素 (ANP)免疫反应的分布状态 ,为探讨ANP在耳蜗中的作用提供形态学基础。方法 :采用免疫组织化学ABC法检测ANP在正常豚鼠耳蜗各组织中的分布特征。结果 :在耳蜗 1～ 4回的血管纹、螺旋缘、Corti’s器、螺旋神经节和中间阶外壁的螺旋韧带均发现有ANP反应 (ANP IR)阳性产物 ;而耳蜗骨壁、前庭膜、鼓阶外壁的螺旋韧带和鼓阶的下壁ANP IR为阴性。结论 :耳蜗中的ANP在内耳淋巴液的生成和声信号的传导以及耳蜗血流量的调节等方面可能担负着重要的作用     

Atrial natriuretic factor (ANF) does not affect ion transport in human intestine but does in porcine intestine

The aim of this study was to test whether atrial natriuretic factor (ANF) exerts any effect on human intestinal ion transport, and the porcine intestine was used as a positive control of ANF's effects. Tissues from human proximal (n = 6) and distal (n = 6) colons, and from distal ileum (n = 6) were mounted in Ussing chambers, and short circuit current (I_sc) was measured subsequent to serosal application of ANF (10^--⁶ m), 8–Br-cyclic guanosine monophosphate (8–Br-cGMP) (10^--⁴ m), and theophylline (10^--² m). ANF did not affect I_sc whereas 8–Br-cGMP increased I_sc by 28 (8–53), 16 (3–36), and 16 (5–41) μA cm^-2 in the distal colon (DC), proximal colon (PC) and distal ileum (DI), respectively. Likewise, transepithelial potential difference (PD) became more negative by 5.0 (0.6–8.9), 2.5 (0.4–4.0) and 0.9 (0.3–2.3) mV in DC, PC, and DI, respectively, subsequent to addition of 8–Br-cGMP. I_sc and PD were further increased by theophylline. Additional radio-isotope flux studies in human colon revealed that ANF did not affect electroneutral sodium and chloride transport either. For comparison, ANF (10^--⁶ m) was administered to large intestinal tissues from young pigs in which ANF induced a significant increase in I_sc which was comparable to the 8–Br-cGMP response in humans. The porcine I_sc response was partly inhibited by chloride-free solution on the serosal side, by serosal application of bumetanide (10^--⁴ m) and BaCl₂ (10^--³ m), and mucosal application of the chloride-channel blocker diphenylamine-2–carboxylate (DPC) (10^--³ m). Mucosal amiloride (10^--⁵ m) pre-treatment reduced baseline I_sc but did not affect the porcine intestinal I_sc response to ANF. In vitro radio-autography demonstrated specific binding sites for ANF in porcine distal colon, whereas no apparent labelling was observed in human distal colon. These findings suggest that the lack of effect of ANF on sodium and chloride transport in human distal ileum and colon is probably due to lack of ANF receptors. In the porcine intestine, however, the I_S0 response induced by ANF seems to involve stimulation of electrogenic chloride secretion, whereas electrogenic sodium absorption seems unaffected.     

起搏负荷超声与常规多普勒超声心动图对冠心病检出率的比较

目的　通过食道心房起搏负荷试验 ,使用彩色多普勒超声心动图对左心室室壁运动状态及左心室舒缩功能改变进行评价 ,以提高冠心病诊断的检出率 ;方法　使用心脏程序刺激仪经食道起搏导管调整心率达次极量 ;同时使用彩色多普勒超声心动仪进行左心室室壁运动记分并记录二尖瓣口及主动脉瓣环部血流频谱 ;结果　经食道心房起搏增加心脏负荷 ,应用左心室每搏量 (SV)、主动脉瓣环部流速积分 (VTIAO)、等容舒张时间 (IVRT)、二尖瓣口流速积分(VTIMV) )、快速充盈分数 (RFI)及室壁运动记分指数 (WMSI)作为指标在冠心病诊断中可提高检出率 ,以WMSI结合其它两项左心室舒缩功能阳性指标 ,其冠心病诊断的检出率为 95 % ,假阳性率为 3% ;结论　经食道心房起搏彩色多普勒负荷超声心动图 (TPDE)在冠心病诊断中有较高的应用价值 ,因其简便、实用和安全 ,宜在临床广泛推广使用     

Determinants of pulmonary blood volume. Effects of acute changes in pulmonary vascular pressures and flow

To examine the effects of pulmonary vascular pressures and flow on pulmonary blood volume (PBV), experiments were performed at constant heart rate and zone 3 conditions (mean left atrial pressure (LAP) above airway pressure) in six anesthetized, open-chest dogs. PBV was calculated as the product of electromagnetic aortic flow and pulmonary mean transit time for ascorbate, obtained without blood withdrawal by polarographic recording of aortic ascorbate changes. In three series of experiments LAP was raised similarly in three steps, from 4.5 to 14.8 mmHg: by mitral constriction which reduced pulmonary blood flow, by blood volume expansion which more than doubled pulmonary blood flow, or by a combination of the two procedures which kept pulmonary blood flow constant. In all three series, LAP and mean pulmonary arterial pressure (PAP) rose in proportion, but PBV was better correlated to PAP (r=0.87±0.02) than to LAP (r=0.66±0.09). These experiments suggest that PAP is the most important factor in determining PBV under zone 3 conditions, whether PAP is raised by increasing pulmonary blood flow or by mitral constriction.     

The location and distribution of type A and type B atrial endings in cats

Summary In the attempt to explain the difference in discharge pattern of atrial endings, 131 endings were localized by punctate stimulation, 44 were type A, 77 type B and 10 of an intermediate type. All were located on the dorsal wall of the atria with none on the ventral wall or in the appendage. On the right side, 74% of type A were located in the atria and 63% of type B in or near the veins. On the left side, 67% of type A and 94% of type B were located in or near the veins. Thus, there appeared to be some difference in the location of type A and type B endings on the right side, but on the left side both types of endings were for the most part confined to the venous region. Further, on both right and left sides, these endings were present both in the central part of the atria and in or adjacent to veins. This leads to the suggestion that the difference in discharge patterns is not caused by the location but may be due to some other reasons, e. g. difference of arrangement in the atrial wall with respect to the contractile elements.     

Responsiveness of the ANP providing system to volume load in conscious dogs

We examined in detail changes in arterial plasma ANP concentration in response to volume load in conscious dogs. In a 5-min volume load experiment, 18 ml/kg of isosmotic and isooncotic 3% Dextran 40 in saline was infused over a period of 5 min. Mean left atrial pressure (MLAP) increased transiently by 7.6±0.9 mm Hg. Plasma ANP level (P-ANP) did not significantly increase. Assayed P-ANP levels were corrected for hemodilution. Corrected P-ANP (C-ANP) significantly increased from 206±17 to 348±34 pg/ml. However, the level of C-ANP did not reach a steady state. No significant linear correlation was found between increases in MLAP and normalized C-ANP. In a 45-min volume load experiment, the elevated level of MLAP caused by the 5-min volume load was maintained for 40 min by supplemental infusion. C-ANP significantly increased from 196±18 pg/ml to 435±73 ng/ml. The level of C-ANP reached a steady state. A close linear correlation was observed between increases in MLAP and normalized C-ANP. However, the peak time of C-ANP lagged 10 min behind MLAP. These results indicate that it takes 10 min for P-ANP to reach a steady state in fully responding to a volume load, and that the long-term volume load is a prerequisite to the response of the ANP providing system.     

Atrial natriuresis under the condition of a constant renal perfusion pressure

An experimental elevation of left atrial pressure (eLAP ) by means of a reversible mitral stenosis is accompanied with an increase in sodium excretion (UNa—) and arterial blood pressure (by about 20 mm Hg, 2.7 kPa), and by a decrease in plasma renin activity.It is well established that an increase in renal perfusion pressure (Pren) can augment UNa—. Therefore the present study was undertaken to examine whether the eLAP -induced natriuresis was caused by the increased Pren. — Four female beagle dogs were kept under controlled environmental conditions. They received asodium rich diet (14.5 mmol/Na/kg/d). The dogs were chronically instrumented: purse string around the mitral annulus, catheter in the left atrium, carotid loop, pneumatic cuff above the renal arteries, pressure transducer below the renal arteries. Pren was kept constant by means of a digital servofeedback control circuit. The dogs served as their own controls (13 experiments without and 15 experiments with a controlled renal perfusion pressure were performed).After eLAP(+1.0 kPa), UNa— rose from 4.1±2.6 to 10.3±3.9 mol Na/min/kg. If Pren was kept constant, the corresponding values were 4.2±2.8 and 9.3±2.9 mol/min/kg. These data clearly indicate that the atrial natriuresis is not mediated by an augmentation of renal perfusion pressure. Therefore these results support the hypothesis that atrial natriuresis probably is due to an eLAP-induced suppression of the renin-angiotensin-system or other natriuretic mechanisms.Abbreviations ADP 3×20 min After distension period - AN Atrial natriuresis - bw kg Body weight - CP 3×20 min Control period - DP 3×20 min Distension period - eLAP kPa Experimental increase of left atrial pressure (during all DP's about +1.0 kPa) - HR l/min Heart rate - LAP kPa Left atrial pressure - n ₁ Number of dogs used - n ₂ Number of experiments (1 expt/day) - n ₃ Number of collection periods (urine) or number of samples (HR) - Part kPa Mean systemic arterial blood pressure (carotid artery) - Pren kPa Mean renal perfusion pressure (aorta, below the renal arteries) - UCI— mol/min/kg Chloride excretion - UK— mol/min/kg Potassium excretion - UNa— mol/min/kg Sodium excretion - Uosm— osm/min/kg Osmolar excretion - — l/min/kg Urine volume Preliminary parts of this work have been presented in Kiel (Spring meeting of the Deutsche Physiologische Gesellschaft, March 1979) and in Stockholm, Sweden (III. European Colloquium on Renal Physiology, June 1979).     

ANF-Konzentrationen und Drücke im kleinen Kreislauf unter Belastung vor und nach Koronardilatation

Summary According to several reports of close correlations between pulmonary artery pressure and ANF plasma levels it would be convenient to replace invasive pressure monitoring by ANF determination.Mean pulmonary artery and right atrial pressures and pulmonary artery as well as peripheral venous ANF plasma concentrations were measured in 24 patients before and after coronary angioplasty (PTCA) continuously at rest and during exercise: At rest, both pressure and ANF-values remained unchanged before and after PTCA. At exercise, there was a decrease of mean pulmonary artery pressure (from 41.3±8.6 to 31.5±7.4 mmHg,p<0.001), mean right atrial pressure (from 11.9±3.0 to 9.0±2.3 mmHg,p< 0.001), pulmonary artery (282.5±191.0 to 207.3±157.2 pg/ml,p<0.05) and peripheral venous (112.7±48.0 to 97.1±53.2 pg/ml, n.s.) ANF concentration after PTCA. We found no correlation between PTCA-induced changes of right arterial pressures and ANF concentrations, while changes of pulmonary artery pressures were significantly correlated to changes of peripheral venous (r=0.79,p<0.001) as well as pulmonary artery (r=0.59,p<0.01) ANF concentrations at exercise. In 6 of the 24 patients, however there was an inverse relationship between changes of pulmonary artery pressures and ANF concentrations. — Our data demonstrate a significant correlation between changes of ANF plasma level and pulmonary artery pressure values at exercise after PTCA. In the individual case however invasive pressure monitoring cannot be replaced by determination of ANF plasma levels.

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Abkürzungsverzeichnis ANF Atrialer natriuretischer Faktor - PTCA Perkutane transluminale Koronarangioplastie - PPa mittlerer pulmonalarterieller Druck - PPc mittlerer pulmonalcapillärer Druck - PRA mittlerer rechtsatrialer Druck Herrn Prof. Dr. med F. Scheler zum 65. Geburtstag gewidmet     

Atrial automaticity and atrioventricular conduction in athletes: contribution of autonomic regulation

Little is known about the sinoatrial automatism and atrioventricular conduction of trained individuals who present a normal resting electrocardiogram. We used transesophageal atrial stimulation, a minimally invasive technique, to evaluate aerobically trained athletes (n=10) and sedentary individuals (n=10) with normal resting electrocardiograms, to test the hypothesis that parasympathetic tone, as detected by heart rate variability, could be associated with changes in sinoatrial automatism and atrioventricular conduction. Corrected sinus node recovery time tended to be longer in athletes than in sedentary individuals, but this difference did not reach statistical significance. The Wenckebach point occurred at a lower rate in athletes than in the controls. Over a 24-h period of measurement, the mean RR interval was longer in the athletes than in the sedentary individuals. The mean square root of successive differences (rMSSD) tended to be higher in athletes than in controls, but this difference did not reach statistical significance. There was a moderate correlation (r=0.48, P < 0.05) between the index of atrioventricular conduction, the rate at the Wenckebach point, and the logarithmically transformed rMSSD. Thus, as a corollary to its effects on the sinus node, where increased parasympathetic tone, decreased sympathetic tone, and non-autonomic components may contribute to sinus bradycardia, it is possible that athletic training may also induce intrinsic adaptations in the conduction system, which could contribute to the higher prevalence of atrioventricular conduction abnormalities observed in athletes. Accepted: 2 January 2000