Endothelin-1 concentrations in clone calves, their surrogate dams, and fetal fluids at birth: association with oxygen treatment

Increased endothelin-1 (ET-1) plasma concentration in human infants is associated with persistent pulmonary hypertension of the newborn, a problem also identified in calves derived from somatic cell clone technology. Increased ET-1 also is present in the amnionic fluid and plasma of the infant and mother in preeclampsia, a condition associated with abnormal placentation. Abnormalities in placentation are identified in clone calves. We measured ET-1 in fetal fluid, calf plasma, and surrogate dam plasma in 40 clone calves at the time of term delivery. Calves were subsequently identified as being either oxygen treated (O2) or non-oxygen treated based on their postpartum clinical course. Fetal fluid ET-1 concentration greater than 1.4 ng/mL carried a 3-fold increase in odds of the calf being treated with oxygen. Maternal plasma ET-1 concentration was greater in the O2 group (13 pg/ mL: [8-23 pg/mL] versus 25 pg/mL [12-40 pg/mL]; median, 25-75 percentile). Plasma ET-1 concentration in calves was not significantly different between groups. Fetal fluid ET-1 may serve as a marker for neonatal disorders of oxygenation in clone calves and the source of ET-1 may be the placenta.     

Cardiovascular effects of topical ophthalmic 10% phenylephrine in dogs

Objective To evaluate the effect of topical ophthalmic 10% phenylephrine on systolic arterial pressure (SAP), diastolic arterial pressure (DAP), mean arterial pressure (MAP), pulse rate (PR) and electrocardiogram (ECG) in dogs. Animals studied Nine clinically normal dogs. Procedure Arterial catheters were placed in the dorsal pedal artery of awake dogs and ECG leads were attached. After a 15‐min acclimatization period, baseline PR, SAP, DAP and MAP were recorded every 5 min for 20 min. Two treatment groups (eight dogs each) were studied. Group I: one drop of phenylephrine was placed in each eye once. Group II: one drop of phenylephrine was placed in each eye three times at 5‐min intervals. Following treatment, PR, SAP, DAP and MAP were recorded every 5 min for 90 min. The mixed procedure of the SAS system was used to perform a repeated measures analysis of variance to test for linear and quadratic trends across time. Results Group I: There was a significant quadratic decrease in PR across time (P = 0.0051). Systolic arterial pressure increased linearly with time (P = 0.0002), MAP increased linearly with time (P = 0.0131), and DAP increased linearly with time (P = 0.0001). Group II: There was a significant quadratic decrease in PR across time (P = 0.0023). There was a significant quadratic increase in SAP (P = 0.0324), MAP (P = 0.0103) and DAP (P = 0.0131) across time. Conclusions Topical ophthalmic application of 10% phenylephrine in normal dogs results in elevation of arterial blood pressure and reflex bradycardia.     

Time-specific intraocular pressure curves in Rhesus macaques (Macaca mulatta) with laser-induced ocular hypertension

Objective To detect and categorize time‐specific variations in daytime intraocular pressure (IOP) found in Rhesus monkeys with laser‐induced ocular hypertension. Procedures Ten male monkeys with argon laser‐induced ocular hypertension in one eye were anesthetized with ketamine hydrochloride, and the IOP measured in both eyes at 7 a.m., 7.30 a.m., and then hourly until 1 p.m. with a Tonopen? XL applanation tonometer. Intraocular pressure time profiles for both eyes in each animal were developed. The means ± SD of the IOPs for both eyes were calculated for the whole 6‐h study period, and the values compared statistically. The difference between the lasered eye mean IOP standard deviation and the normal eye mean IOP standard deviation for each animal during the 6‐h follow‐up was also calculated and compared. Results Mean IOP (± SD) in the glaucoma and normal eyes for the 10 animals during the 6‐h study was 32.6 ± 2.5 and 14.9 ± 2.5 mmHg, respectively. The IOP was significantly higher in the experimental eye than in the normal eye (P = 0.0008). The mean IOP in the lasered eye did not significantly change during the study period, whereas a slight but significant increase in IOP of the normal eye over the study period was recorded (P = 0.003). The variance in IOP in the hypertensive eyes was considerably greater than that in the untreated control eyes. From 7 a.m. to 1 p.m. the IOP declined in five eyes and increased in the other five eyes with laser‐induced ocular hypertension. Conclusions The time‐specific IOP variation pattern in the daytime in the laser treated eyes is significantly greater than the variation in the normotensive eyes. This shows that in order to detect statistical differences between IOP variations induced by an IOP‐reducing drug, and the exaggerated spontaneous IOP variations present in the laser‐induced hypertensive eye, sufficient animals should be included in any study. Understanding the time‐specific IOP variation present in a group of monkeys with laser‐induced ocular hypertension is essential prior to using the model for the evaluation of IOP‐reducing drugs.     

Ca2+-activated Cl- channels and pulmonary hypertension induced by high pulmonary blood flow

Pulmonary hypertension induced by high pulmonary blood flow involves a variety of complex mechanisms, including endothelial damage, pulmonary artery smooth muscle relaxation-contraction disorder and vascular remodeling. Besides, the factor of ion channels in pulmonary artery smooth muscle cells is also highly correlated to vasoconstriction. In recent years, many studies have shown that activation of Ca²⁺-activated Cl^- channels is responsible for the membrane depolarization of pulmonary artery smooth muscle cells, and plays an important role in the regulation of vascular tone and vasoconstriction. This article reviews the biophysical and pharmacological characteristics of Ca²⁺-activated Cl^- channels as well as the influence of Ca²⁺-activated Cl^- channels in high pulmonary blood flow-induced pulmonary hypertension.     

一氧化氮对肉鸡肺动脉高压综合征的影响

肺动脉压升高是肉鸡肺动脉高压综合征(PHS)的重要发病机制。近年来研究表明一氧化氮(NO)在PHS发生发展中发挥着重要作用。本文论述了NO对肉鸡PHS发病过程的影响。一氧化氮合酶(NOS)和NO活性在PHS早期升高而后期下降。NO具有强大的扩张血管的作用,但在PHS过程中,NO合成相对不足,导致肺血管舒缩失衡,引起肺动脉压升高。肺血管重构是肉鸡肺动脉高压综合征的重要病理学变化特征,而NO可促进肺小动脉平滑肌细胞凋亡,在一定程度上抑制肺血管重构的形成。NO作为自由基对机体造成的损伤也是引起PHS的原因之一。在肉鸡日粮中补充NO前体物L-精氨酸可以增加内源性NO的生成,有助于降低PHS的发病率。     

不同能量和蛋白质水平日粮对妊娠期湘东黑山羊血液生化指标的影响

为研究不同能量和蛋白质水平日粮对妊娠期湘东黑山羊血液生化指标的影响,选取中等体况(30 kg±4 kg)的湘东黑山羊120只进行同期配种,再从怀孕母羊中挑选100只分为10组,每组10只,根据母羊妊娠生理阶段,将其分为妊娠前期(前90 d)和妊娠后期(后60 d)两个阶段进行饲喂试验,以能量和蛋白质作为因子,蛋白水平设A、B、C、D、E五个组,梯度为10 g;能量水平设V、W、X、Y、Z五个组,梯度为0.5 MJ。结果表明:日粮不同能量水平对妊娠母羊血糖、胰岛素和甘油三酯含量均有明显影响;日粮不同蛋白质水平对妊娠母羊血清尿素氮和总蛋白均有明显影响。