DIFFERENCES IN ENDOTHELIUM-DEPENDENT RELAXATION IN VARIOUS ARTERIES FROM WATANABE HERITABLE HYPERLIPIDAEMIC RABBITS WITH INCREASING AGE

1. Endothelium-dependent relaxation in response to acetylcholine (ACh) and the calcium ionophore A 23187 was examined in aorta, coronary, basilar and renal arteries isolated from Watanabe heritable hyperlipidaemic (WHHL) rabbits of 2, 6 and 12 months of age, with normolipidaemic heterozygous WHHL rabbits as controls. 2. In the rings of WHHL rabbit aortae and coronary arteries preconstricted with vasoconstrictors, endothelium-dependent relaxation in response to ACh was attenuated with age compared to the heterozygous WHHL rabbits. A significant negative correlation was found between the total cholesterol content and the relaxation response to ACh in the aortae or coronary arteries from 6 and 12 month old WHHL rabbits. 3. In the rings of basilar arteries, endothelium-dependent relaxations to ACh were not modified with age. Similarly, in the rings of renal arteries, the relaxation response to ACh was not changed with age, but in the 6 and 12 month preparations, after the age of 6 months, a contraction following the relaxation appeared at higher concentrations of ACh (10^?7 to 10^?6 mol/L). The contraction was endothelium-dependent and inhibited by indomethacin. 4. A 23187-induced endothelium-dependent relaxations were also markedly attenuated in the aorta and significantly in the coronary artery with age. 5. Endothelium-independent relaxation to sodium nitroprusside was not changed in all arteries from WHHL rabbits of different ages. 6. These findings indicate that in the aorta and coronary artery of the WHHL rabbit, the endothelium-dependent relaxation to ACh and A 23187 becomes impaired with increasing age (i.e., with the progression of cholesterol deposition in the arterial wall) but is preserved in the basilar and renal artery.     

INTERACTIONS BETWEEN THE CIRCULATORY EFFECTS OF CENTRAL HYPOVOLAEMIA AND ARTERIAL HYPOXIA IN CONSCIOUS RABBITS

1. Eight conscious rabbits were repeatedly subjected to progressive reduction in central blood volume by gradually inflating a thoracic inferior vena caval-cuff so cardiac index (CI) fell at a constant 8.5% of baseline/min. 2. Caval-cuff inflations were performed after 10 min exposure to 100, 21, 12–14 and 8–10% O₂, with and without the addition of 3–4% CO₂, in randomized order. 3. The haemodynamic response to progressive reduction in central blood volume was biphasic. In Phase I, systemic vascular conductance index (SVCI) fell linearly, supporting mean arterial pressure (MAP). When CI had fallen to a critical level, Phase II occurred in which SVCI rose abruptly, MAP plummeted and respiratory drive progressively increased. 4. During Phase I, there were independent linear relationships between Pao₂ (but not Pao₂) and the rates at which SVCI and MAP changed during the progressive fall of CI. The higher the level of Pao₂, the greater was the rate of fall of SVCI and the less the rate of fall of MAP. 5. There was an inverted U-shaped effect of Pao₂, on the level of CI at which Phase II occurred: (a) during hyperoxia (100% O₂), Phase II occurred later than during normoxia (21% O₂); and (b) across the normoxic and hypoxic gas mixtures (21–8% O₂, with and without added CO₂), there was an independent linear relationship between Pao₂ (but not Pao₂ or Pao₂×Pao₂) and the level of CI at which Phase II occurred. That is, the lower the level of Pao₂, the later was the onset of Phase II. This interaction is best explained by an increased level of central sympathetic vasoconstrictor drive during hypoxia.     

实验性骨折愈合中骨吸收活动的超微结构观察

将50只家兔造成实验性桡骨骨折,分批取骨痂标本,用光镜和电子显微镜观察表明,在骨折愈合过程中,破骨细胞是骨吸收的主要执行者,巨噬细胞能吞噬死骨,但不能吸收骨质。     

VASOCONSTRICTION IN THE RENAL VASCULAR BED DURING EXERCISE: STUDIES IN CONTROL AND HEART FAILURE RABBITS

1. The effects of graded treadmill exercise on renal blood flow (RBF) were examined in seven rabbits, in which congestive heart failure (CHF) was produced by the administration of doxorubicin, 1 mg/kg, twice weekly for 8 weeks, and in seven controls. A third group of five rabbits underwent doxorubicin treatment with the addition of surgical section of the left renal sympathetic nerve. 2. During submaximal exercise, there was a small reduction in RBF in controls, which was greatly exaggerated in CHF. 3. In both control and heart failure rabbits, there was a precipitous fall in RBF as exercise fatigue developed. 4. Renal sympathectomy ablated these changes in RBF during exercise. 5. It is concluded that in heart failure there is an exaggerated, sympathetically mediated, diversion of blood flow away from the kidney. The onset of exercise fatigue in both normal and heart failure rabbits is accompanied by a marked intensification of this process.     

改良后的家兔动脉深低温保存实验研究

目的：为探讨家兔动脉在改良的深低温保存后，其作为血管材料替代物的优越性。方法：无菌条件下取新鲜兔动脉，分别给予改良后的营养液经慢速深低温冷冻和快速深低温冷冻处理，6个月后异体和自体移植，12周后，取移植的血管组织，观测其组织活性，组织形态、血管通畅率。结果：改良的营养液保护的血管经慢冻法处理后与自体血管活性相近，经改良的营养液保护的血管，移植前后血管内膜的连续性，血管的组织结构良好；慢冻法处理的血管通畅率比速冻法处理的高，与自体移植组相当。结论：复方氨基酸可以替代传统冷冻保护液中的小牛血清用于血管的深低温保存，降低了该保存技术的成本；快速深低温冷冻保存的动脉血管活力移植效果不如慢速冷冻处理的异体动脉好。     

Laser irradiation and balloon dilatation in experimental transluminal angioplasty

Percutaneous transluminal balloon angioplasty (PTA) is being currently used in patients with coronary artery disease. Laser irradiation (LI) has been effective in vaporizing atherosclerotic plaques. The purpose of this work was twofold: to compare PTA and LI techniques in the recanalization of experimental obstructive arterial lesions, and to evaluate the possibility of reducing the failures and local complications and increasing the success rate of PTA by the combined use of LI. Atherosclerotic iliac stenoses were induced in 27 rabbits; lesions were evaluated angiographically before and after intervention and were studied histologically and by electron microscopy. Argon-ion LI delivered through microlens-tip optic fibers reduced the stenotic area from 64.2 +/- 21.8% to 40.3 +/- 10.7% (n = 10, P less than .01) and PTA from 60.7 +/- 15.9% to 30.4 +/- 7.7% (n = 9, P less than .01). However, percentage reduction was higher in PTA-treated stenoses (48.4 +/- 10.1% vs 34.5 +/- 13.5%, P less than .0125). In eight more rabbits, low power LI (4.55 +/- 1.25 J) was delivered after PTA in dilated segments. Post-PTA LI further decreased stenoses (from 31.2 +/- 7.8% to 29.1 +/- 8.1%, P less than .0125); laser-irradiated segments showed diffuse carbonization of the disrupted intimal layer. The normalized transtenotic pressure gradient decreased significantly in all groups: LI reduced the gradient from .40 +/- .25 to .17 +/- .07 (P = .005); PTA from .37 +/- .14 to .11 +/- .04 (P = .001); LI after PTA from .40 +/- .16 to .12 +/- .06 (P = .001). Thus, LI is effective (less than PTA) in relieving experimental atherosclerotic stenoses and seems useful when combined with PTA.     

Genetic susceptibility to herpetic encephalitis of inbred rabbits of B/Jas strain

Inbred rabbits of B/Jas strain were found to be highly susceptible to herpes simplex virus type 1 encephalitis, following i.v. injection of the virus, while Chbb:HM strain rabbits were not susceptible. The susceptibility trait seemed to be inherited recessively, involving multiple genes, because (B/Jas x Chbb:HM)Fl hybrids were as resistant as Chbb:HM rabbits, and because more than 90% of backcrosses of (B/Jas x Chbb: HM)FI to B/Jas were resistant to viral inoculation. The encephalitis in B/Jas rabbits resembled human herpes simplex encephalitis, in that the temporal lobe as well as the brain stem were affected preferentially, leading to the development of various types of seizures, such as circling, loss of balance leading to a fall, and tonic and clonic convulsions. The disease could be diagnosed by magnetic resonance imaging (MRI) analysis before onset of seizures, and diseased rabbits showed a marked lymphopenia at onset of seizures. © 1995 Wiley-Liss, Inc.     

家兔实验性减压病时血浆中血拴素A_2及前列环素含量的变化

实验观察了“安全”减压和不适当减压条件下家兔减压病(DCS)的发病情况、Doppler超声以及血浆中TxB_2和6-keto-PGF_(1a)的变化;还观察了消炎痛对DCS的预防怍用。结果显示:减压愈不当,DCS发病愈重,Doppler超声气泡探测仪检测到的级别愈高。血浆TxB_2、6-keto-PGF_(1α)值在濒死动物中明显升高(P<0.01);存活动物中,TxB_2经历了下降、再恢复的过程(P<0.01),而6-keto-PGF_(1α)值未见明显变化。消炎痛在抑制血浆TxB_2升高的同时,有效地降低了DCS发病率。此结果表明:TxA_2、PGI_2参与了重型DCS的发病过程,消炎痛的顶防作用与抑制花生四烯酸代谢物的生成有关。     

Experimental studies on preventive effects of API0134 on vessel reocclusion after thrombolysis

Summary 24 model rabbits with femoral arterial thrombosis were divided into two grocps: the treatment group consisting of 12 rabbits which received API₀₁₃₄. and the control group composed of another 12 rabbits. 2 hours after recanalization by urokinase thrombolysis, reocilusion occurred only in 1/12 vessel (8%) with incomplete occlusion in the treated group, but in 8/12 (67%) with complete occlusion in the control group as assessed by angiograsphy. Pathological examination of specimen taken 24 hours after thrombolysis showed that 6/12 (50%) of the treated group gave the evidence of thrombus occlusion, and milder intimai injury and less adhered blood cells than in the control group, 83% of which had thrombus occlusion. In comparision with the control group, the function of platelet in the treated group demonstrated lower platelet aggregation rate (PAgR) and plasma thromboxane A₂ (TXA₂) level, higher prostacyclin (PGI₂) and plasminogen activator (PA) activity as well as lower plasminogen activator inhibitor (PAI) activity. From the above it may be concluded that the preventive effect of API₀₁₃₄ on reocclusion might be due to inhibition of platelets aggregation and promotion of fibrinolysis.     

磁场对家兔急性实验性高血压的影响

目的 :探讨内关穴敷磁的降压效应。方法 :40只清醒家兔和 40只麻醉家兔 (其中 2 0只去减压神经 ) ,静脉注射去甲肾上腺素或苯肾上腺素引起急性实验性高血压 ,并于内关穴敷磁 (0 .1～ 0 .2T) ,记录血压、心率和敷磁前及 1h后的血液粘度的变化。结果 :敷磁 1h后各实验组平均动脉压 (MAP)显著下降 (P <0 .0 1)。麻醉和清醒家兔MAP降幅无差异 (P >0 .0 5 ) ,但显著高于去减压神经家兔MAP的降幅 (P <0 .0 1或 0 .0 5 ) ,各实验组全血比粘度显著下降 (P <0 .0 1或 0 .0 5 ) ,实验组与各自对照组心率敷磁前后无差异 (P >0 .0 5 )。结论 :磁场具有降压作用 ,但对心率无影响 ,其降压效应与减压神经的抑制和全血粘度的降低有关 ,与化学感受性升压反射无关