2种组胺受体拮抗剂对低温诱发的肉鸡肺动脉高压的影响

为探讨组胺H1受体拮抗剂扑尔敏和H2受体拮抗剂西咪替丁对低温诱发的肉鸡肺动脉高压的影响,并由此推测组胺在低温诱发的肉鸡肺动脉高压形成过程中的作用。140只17日龄AA肉鸡随机分为4组。(1)常温组:40只在常温条件下饲养(22～23℃),每日注射生理盐水2次;(2)低温组:40只在低温环境中饲养(9～11℃),每日注射生理盐水2次;(3)扑尔敏组:40只在低温环境中饲养(9～11℃),每日注射扑尔敏2次;(4)西咪替丁组:20只在低温环境中饲养(9～11℃),于24日龄至38日龄期间每日注射西咪替丁2次。分别于低温处理后1周(24日龄)、2周(31日龄)、3周(38日龄)、4周(45日龄)从常温组,低温组,扑尔敏组中各随机抽取10只,西咪替丁组在低温处理后2周(31日龄)、3周(38日龄)各随机抽取10只,称取体重,然后利用右心导管法测定肺动脉压(PAP),并测定红细胞压积(PCV),腹水心脏指数(AHI)。结果发现:(1)24日龄、31日龄、38日龄时,低温组肺动脉收缩压,舒张压显著高于(P<0105)或极显著高于(P<0101)同日龄常温组。24日龄时扑尔敏组肺动脉收缩压显著低于(P<0105)同日龄低温组。38日龄时西咪替丁组肺动脉收缩压,舒张压极显著低于(P<0101)同日龄低温组。(2)24日龄、31日龄、38日龄、45日龄时,低温组PCV极显著高于(P<0101)同日龄常温组。24日龄时扑尔敏组     

卡托普利对腹水综合征肉鸡右心功能的影响

150只15日龄AA肉鸡随机分为常温组、低温组和卡托普利组,探讨卡托普利对腹水综合征肉鸡右心功能的影响。结果:卡托普利降低低温诱发肉鸡腹水的发生率;卡托普利降低低温诱发肉鸡肺动脉高压;卡托普利与低温组比降低肉鸡腹水心脏指数;28、36日龄和44日龄,卡托普利组右心室收缩压低于低温组(P0.05);28、36日龄和44日龄,卡托普利组右心室舒张压分别极低于低温组((P0.01)。本试验证明卡托普利可以降低腹水发生率和右心肥大,有效维护右心功能。     

低温诱发肉鸡腹水综合征发生过程中肺血管重塑与肺动脉高压的关系

将160只15日龄雄性AA商品代肉鸡随机分为对照组((22±1.5)℃)和低温组((11±2)℃)。15~50日龄,每组每周随机取6只,以右心导管法直接测定肺动脉压(PAP),并取肺组织做石蜡切片进行Weigert-间苯二酚复红染色,分析肺血管重塑情况。50日龄时统计整个饲养过程中肉鸡腹水综合征(AS)发生率。结果显示,低温组肉鸡AS发生率(18.75%)极显著高于对照组(1.25%)(P<0.01);低温组肉鸡PAP从22日龄开始较对照组明显升高(P<0.01或P<0.05);20~50、50~100、100~200μm肺动脉结构分别从36、43、43日龄开始较对照组发生了明显的重塑(P<0.01或P<0.05)。结果表明,低温诱发肉鸡AS过程中出现了明显的PAP升高和肺血管重塑,且肺动脉高压(PH)促进了肺血管重塑,肺血管重塑加剧了PAP升高。     

早期限饲对肉鸡血浆NO水平、红细胞比容和心脏指数的影响

试验测定了常温和低温下限饲肉鸡和非限饲肉鸡体内一氧化氮(NO)含量、红细胞比容(PCV)和心脏指数的变化,以探讨早期限饲降低肉鸡肺动脉高压综合征(PHS)发病率的机理。试验结果显示低温下肉鸡的PCV值、心脏指数和PHS的发病率显著升高,NO水平在低温早期显著降低,然而随着低温时间的延长,低温处理组肉鸡的血浆NO水平反而代偿性升高。早期限饲显著降低了肉鸡生长早期的红细胞压积值,并显著降低了42日龄心脏指数和PHS的发病率。限饲鸡在限饲期间血浆NO水平显著降低,但其他阶段与非限饲鸡差异不显著。这提示早期限饲能够缓解肉鸡肺动脉高压和右心肥大的产生,其机理可能与NO和PCV改变所致的血流动力学变化有关。     

两种组胺受体拮抗剂对肺动脉高压肉鸡右心功能的影响

探讨组胺H,受体拮抗剂扑尔敏和H。受体拮抗剂西咪替丁对低温诱发肺动脉高压肉鸡右心功能的影响,由此反证内源性组胺在低温诱发肉鸡肺动脉高压形成过程中的作用。采用160只17日龄AA肉鸡随机分为4组,每组40只。（1）常温组：在常温条件下饲养（22～23℃）,每天注射生理盐水2次;（2）低温组：低温环境中饲养（9～11℃）,每天注射生理盐水2次;（3）扑尔敏组：与低温组相同饲养,每天注射扑尔敏2次;（4）西眯替丁组：与低温组相同饲养,每天注射西眯替丁2次。分别于低温处理后1周（24日龄）、2周（31日龄）、3周（38日龄）、4周（45日龄）从每组中各随机抽取7只,利用右心导管法测定右心室内压和右心室压最大变化速率,计算腹水心脏指数（AHI）和右心衰竭率。剖杀后用常规阿尔新蓝法对心脏中肥大细胞（MC）染色,免疫组化方法显示组胺。结果：（1）低温处理后使肉鸡肥大细胞和组胺阳性细胞数量显著降低,但2种组胺受体拮抗剂对肥大细胞数量及组胺阳性细胞数无明显影响;（2）扑尔敏组肉鸡右心内压相对稳定,45日龄时右心室舒张压显著低于低温组（P〈0．05）。西咪替丁组肉鸡右心收缩压和舒张压处于较低水平,且在31和38日龄时显著低于低温组（P〈0．05）;（3）扑尔敏组右心内压最大变化速率相对稳定,31日龄时显著低于低温组（P〈0．05）,而45日龄时显著高于低温组（P〈0．05）。西咪替丁组右心内压最大变化速率处于较低水平;（4）45日龄时,扑尔敏组AHI显著低于低温组（P〈0．05）;（5）扑尔敏组显著（P〈0．05）降低了右心肥大指数和右心衰竭发生率,西咪替丁组仅显著（P〈0．05）降低了右心衰竭率。以上结果表明,内源性组胺可能通过H3受体介导肉鸡右心肥大和衰竭,从而促进肺动脉高压综合征的发生发展。     

维拉帕米对低温诱发腹水综合征病鸡右心功能的影响

300只15日龄商品肉仔鸡随机分为常温组、低温组和维拉帕米组，以研究L型电压依赖性钙通道拮抗剂维拉帕米对腹水综合征病鸡右心功能的影响。结果，与低温组相比，维拉帕米可显著降低肉鸡腹水综合征的发生率；维拉帕米组肉鸡腹水心脏指数分别在29、36、43和50日龄时显著或极显著降低；右心室收缩压在36和43日龄时极显著降低，右心室舒张压在36和43日龄时也显著或极显著下降；右心室内压最大变化速率在43日龄时极显著升高。结果表明，维拉帕米可显著降低肉鸡腹水和右心肥大的发生，能有效维护右心功能。     

37℃热应激对实验性大肠杆菌病肉鸡肺动脉压和右心功能的影响

160只商品代AA肉仔鸡于29日龄时随机均分为常温对照组、热应激对照组、常温感染组和热应激感染组．研究了37℃热应激对实验性感染大肠杆菌肉鸡肺动脉压和右心功能的影响。结果37℃热应激1～3d极显著降低（P〈0．01）肉鸡感染大肠杆菌引起的肺动脉高压，肺动脉收缩压、舒张压和平均肺动脉压分别下降了34．78％、45．83％、40．48％。热应激3、7d，感染大肠杆菌肉鸡右心室收缩压显著下降（P〈0．05，P〈0．01），分别下降了26．60％、28．00％，右心室收缩和舒张压最大变化速率显著下降（P〈0．05），分别下降了77．50％，50．77％和75．00％、50．58％。结果表明，37℃热应激可以拮抗肉鸡感染大肠杆菌引起的肺动脉高压，降低感染肉鸡死亡率，但使右心功能下降。     

两种钙颉颃剂对肉鸡肺动脉高压和右心肥大的影响

为了揭示肉鸡肺动脉高压的形成机理,为预防和治疗肉鸡腹水综合征提供理论依据,试验研究了两种钙颉颃剂硝苯地平和维拉帕米对肉鸡肺动脉高压和腹水肉鸡右心肥大指数的影响.结果表明:44日龄,硝苯地平组肺动脉压极明显低于低温组(P<0.01);28和36日龄,维拉帕米明显降低肺动脉压 (P<0.05);44日龄维拉帕米组肺动脉压极明显低于低温组(P<0.01).硝苯地平和维拉帕米可降低肉鸡腹水心脏指数.结果说明维拉帕米和硝苯地平降低了低温诱发的肺动脉高压和肉鸡腹水综合征的发生率,降低肉鸡腹水心脏指数,初步证实钙信号参与了肺动脉高压的形成.     

高盐负荷诱发肉鸡肺动脉高压-腹水综合征

为探讨肺动脉高压在高盐负荷所致肉鸡腹水综合征发生发展的作用。将160只AA商品代肉仔鸡常规饲养至7日龄,随机分成对照组和试验组(饮水中添加0.30%氯化钠),分别于处理后1、2、3、4、5、6周,每组随机抽取8只鸡,利用右心导管法测定平均肺动脉压(mPAP),用温氏法检测红细胞压积(PCV),同时测定腹水心脏指数(AHI),统计腹水发生率。结果表明:(1)高盐负荷诱发肉鸡肺动脉高压,高盐处理1周试验组肉鸡肺动脉压升高为2.91±0.29kPa,显著高于对照组2.18±0.40kPa(P<0.05);并在整个处理期间持续升高,均显著(P<0.05)或极显著(P<0.01)地高于对照组;(2)高盐负荷诱发肉鸡AS,整个试验期间试验组的累计腹水发生率(16.3%)极显著高于对照组(2.5%)(P<0.01);(3)自分组后1周试验组的红细胞压积显著(P<0.05)或极显著(P<0.01)高于对照组,且与mPAP极显著相关(15～50日龄,r=0.612,P<0.01);(4)高盐负荷诱发肉鸡右心肥大,处理后2周试验组的AHI显著增高(P<0.05),与mPAP显著相关;并在整个处理期间相关程度逐渐密切(22日龄,r=0.532,P<0.05;50日龄,r=0.756,P<0.01)。这些结果说明肺动脉高压是高盐负荷所致肉鸡AS的中心环节,并且与右心肥大密切相关。     

环境低温和T3对肉鸡内皮素、一氧化氮和肺动脉压的影响

20 0只 AA肉鸡随机等分为对照组 (C)和试验组 (T) ,C组和 14日龄前 T组鸡按常规饲养。 T组自 14日龄起舍温从 2 5℃起每天降 1～ 2℃逐渐降至 12℃ ,同时在日粮中按 1.5 m g/ kg的剂量添加三碘甲腺原氨酸 (T3 )以诱发肺动脉高压综合征 (PHS)。分别于 2 1、2 8、35、42、49日龄测定 2组肉鸡平均肺动脉压 (m PAP)、红细胞压积 (PCV)、右心全心比 (RV/ TV)、血浆内皮素 (ET- 1)及一氧化氮 (NO)水平 ,同时记录 PHS发病率。结果显示 ,试验组肉鸡 m PAP升高 ,PHS发病率增加 ;PCV、RV/ TV及血浆 ET- 1水平与对照组相比都显著升高 (P<0 .0 1) ;m PAP变化与血浆 ET- 1含量变化之间存在显著正相关 ,2组间血浆 NO水平无显著差异 (P>0 .0 5 ) ,但都出现随日龄增加血浆 NO水平升高的现象。     

Characteristics of the in vitro hypoxic pulmonary vasoconstrictor response in isolated equine and bovine pulmonary arterial rings

OBJECTIVE: Hypoxaemia accompanies dorsal recumbency in the horse and frequently complicates general anaesthesia. The physiology associated with this phenomenon is poorly understood. One possible cause of poor tolerance to dorsal recumbency is an absent or reduced response to hypoxic pulmonary vasoconstriction (HPV). This study compared the HPV response in isolated pulmonary artery vessels from equivalent regions of equine and bovine lung. ANIMALS: Equine and bovine, in vitro study. MATERIALS AND METHODS: Equine and bovine pulmonary arteries were removed from the lungs of euthanased horses and cattle. Measurements of isometric tension were made on isolated rings of pulmonary vessels at 37 degrees C in a Krebs' saline solution. Hypoxia was induced by bubbling with a nominally 0% O(2) gas mixture. RESULTS: A significant HPV response was observed above a baseline tension induced by phenylephrine (PE; 0.3 microm) or 5-hydroxytryptamine (5-HT; 0.1 microm). The HPV response in equine pulmonary vessels was approximately 33% less than the response observed in equivalent bovine vessels (equine 196 +/- 20%versus bovine 290 +/- 32%; p < 0.05). Removal of the endothelium (by rubbing the luminal surface) significantly reduced but did not abolish the HPV response. Incubation with the nitric oxide (NO) synthase inhibitor N-nitro-l-arginine methyl ester (L-NAME; 100 microm), or COX-1/COX-2 inhibitor indomethacin (10 microm) markedly attenuated the HPV response in equine vessels. CONCLUSIONS: These results suggest that a significant HPV response exists in isolated equine pulmonary vessels; a component of this response requires a functional endothelium. Inhibition of cyclooxygenase and NO synthase attenuated the response, suggesting the involvement of a COX product and/or NO in mediating this effect either directly or indirectly. Alternatively, a non-COX related action of the nonsteroidal anti-inflammatory drug, indomethacin, may be involved.     

COMPUTED TOMOGRAPHY ANGIOGRAPHY FOR EVALUATION OF PULMONARY EMBOLISM IN AN EXPERIMENTAL MODEL AND HEARTWORM INFESTED DOGS

This study was performed to characterize pulmonary embolism with computed tomography pulmonary angiography in experimental pulmonary embolism and heartworm infected dogs. In the experimental group, there were pulmonary changes after pulmonary embolism induction as follows: hypoattenuating round filling defects in pulmonary arteries, arterial dilations with straight and abrupt cut‐off appearances in the pulmonary embolism regions, pulmonary infarctions, a cavity formation and spontaneous pneumothorax, and emboli migration. In the heartworm‐infected group, three out of eight dogs developed pulmonary embolism, especially in the right caudal arteries. Arterial dilations with typical tortuosity were also identified, mainly in the right caudal arteries in five dogs. Computed tomography pulmonary angiography can be an important imaging modality in the diagnosis of pulmonary embolism and the evaluation of pulmonary arterial and parenchymal changes in dogs.     

RADIOGRAPHIC FINDINGS IN DOGS WITH SPONTANEOUS PULMONARY THROMBOSIS OR EMBOLISM

Thoracic radiographs of 21 dogs with necropsy-confirmed pulmonary thrombosis or embolism (PTE) were reviewed. Two major lung patterns were seen: (1) regional oligemia, giving the impression of a hyperlucent zone; (2) alveolar pulmonary infiltrate, indicating hemorrhage or infarction. Hemorrhage and infarction could not be differentiated radiographically. Other common findings were attenuation or loss of visualization of a lobar artery or lobar vein and pleural effusion, particularly with infarction and cardiac disease. PTE was often associated with renal disease (glomerulonephritis, amyloidosis), septic processes, pancreatitis, systemic venous or right heart thrombosis, cardiac insufficiency, and hypercorticism.     

GENERALIZED EXTENSIVE IDIOPATHIC PULMONARY OSSIFICATON IN A DOG: A CASE REPORT

A 9-year-old dog was presented with generalized extensive pulmonary mineralization associated with exertional dyspnea and cyanosis. The differential diagnosis for the pulmonary mineralization included metastaticand dystrophic pulmonary calcification, atypical pulmonary neoplasia, alveolar microlithiasis, idiopathic pulmonary mineralization, and idiopathic pulmonary ossification. The dog was euthanized at the owner's request. The histologic diagnosis was idiopathic pulmonary ossification. No previous report of generalized extensive idiopathic pulmonary ossification was found. Idiopathic pulmonary ossification occurs in man, usually involves a limited area of lung, and is functionally unimportant. The pulmonary ossification in the dog reported here was generalized and associated with severe pulmonary dysfunction. The disease in man and that in the dog in this report do not appear to be directly comparable.     

RADIOGRAPHIC AND HISTOPATHOLOGIC CHARACTERISTICS OF PULMONARY FIBROSIS IN NINE CATS

Pulmonary fibrosis is a progressive fatal interstitial lung disease that is often idiopathic, occurs in multiple species, and may be caused by a number of inciting factors. The purpose of this retrospective, multicenter study was to describe the radiographic and histopathologic characteristics of idiopathic and induced pulmonary fibrosis in a group of cats. Cats with thoracic radiographs and histopathologically confirmed pulmonary fibrosis were recruited using the American College of Veterinary Radiology list serve. A board‐certified veterinary radiologist and diagnostic imaging intern reviewed radiographs and recorded characteristics by consensus. Findings from additional imaging modalities were also recorded when available. All histopathology samples were re‐reviewed by a veterinary pathology resident. A total of nine cats met inclusion criteria. All patients had a broad range of radiographic characteristics that included broncho‐interstitial pattern, alveolar pattern, pulmonary masses, pulmonary bullae, pleural effusion, and cardiomegaly. Cats with available echocardiographic studies had characteristics that included right ventricular dilation and hypertrophy and pulmonary arterial hypertension interpreted to be secondary to primary lung disease. Cats with available CT studies had characteristics that included focally increased soft tissue attenuation, masses, and ventral consolidation that exhibited no improvement with dorsal versus ventral recumbency. Histopathology showed pulmonary fibrosis, type II pneumocyte hyperplasia, and smooth muscle hypertrophy in all patients. Epithelial metaplasia was present only in one patient. Findings from the current study indicated that cats with pulmonary fibrosis have highly variable radiographic characteristics and that these characteristics may mimic other diseases such as asthma, pneumonia, pulmonary edema, or neoplasia.     

Calcium antagonists,diltiazem and nifedipine,protect broilers against low temperature‐induced pulmonary hypertension and pulmonary vascular remodeling

This study was designed to determine whether calcium antagonists, diltiazem and nifedipine, can depress low temperature‐induced pulmonary hypertension (PH) in broilers (also known as ascites) and to characterize their efficacy on hemodynamics and pulmonary artery function. Chicks were randomly allocated into six experimental groups and orally administered with vehicle, 5.0 mg/kg body weight (BW)/12 h nifedipine or 15.0 mg/kg BW/12 h diltiazem from 16 to 43 days of age under low temperature. The mean pulmonary arterial pressure (mPAP), the ascites heart index (AHI), the erythrocyte packed cell volume (PCV) and the relative percentage of medial pulmonary artery thickness were examined on days 29, 36 and 43. The data showed that administration of diltiazem protected broilers from low temperature‐induced pulmonary hypertension and vascular remodeling. Although nifedipine prevented mPAP from increasing during the early stage, it did not suppress the development of PH during the late stage and did not keep heart rate (HR), PCV, AHI and the thickness of pulmonary small artery smooth muscle layer at the normal levels. Taken together, our results showed that diltiazem can effectively prevent low temperature‐induced pulmonary hypertension in broilers with fewer side‐effects and may be a potential compound for the prevention of this disease in poultry industry.     

一氧化氮对肉鸡肺血管重塑影响的研究进展

肺血管重塑是肉鸡肺动脉高压综合征的重要病理学变化特征,虽然对其形成的机制尚未完全清楚,但众多细胞因子在其形成过程中起重要作用已得到共识。一氧化氮作为一种信号物质,在血管扩张、细胞增殖与凋亡、内皮素分泌与合成以及抗氧化等过程中发挥着重要的调控作用,显示了其在抑制肉鸡肺血管重塑、预防和治疗肺动脉高压发生方面有着广阔的应用前景。     

Ventilation distribution assessed with electrical impedance tomography and the influence of tidal volume,recruitment and positive end-expiratory pressure in isoflurane-anesthetized dogs

Objective

To examine the intrapulmonary gas distribution of low and high tidal volumes (V_T) and to investigate whether this is altered by an alveolar recruitment maneuver (ARM) and 5 cmH₂O positive end-expiratory pressure (PEEP) during anesthesia.