A theoretical description of arterial pressure-flow relationships with verification in the isolated hindlimb of the dog

We developed and tested a new two-compartment serial model of the arterial vasculature which unifies the capacitance (downstream arterial compliance) and waterfall (constant downstream pressure load) theories of blood flow through the arteries. In this model, blood drains from an upstream compliance through a resistance into a downstream compliance which empties into the veins through a downstream resistance which terminates in a constant pressure load. Using transient arterial pressure data obtained from an isolated canine hindlimb preparation, we tested this model, using a stop-flow technique. Numerical parameter estimation techniques were used to estimate the physiologic parameters of the model. The downstream compliance was found to be more than ten times larger than the upstream compliance and the constant pressure load was significantly above venous pressures but decreased in response to vasodilation. Our results support the applicability of both the capacitance and waterfall theories.     

Histaminergic vasodilatation in the hindlimb of the dog

Summary In 26 dogs under chloralose anesthesia and neuromuscular blockade the hind limbs were vascularly isolated and perfused at constant flow. Electrical stimulation of the intact spinal ventral roots (L_5,6,7) induced: 1. a decrease of the perfusion pressure (PP) in the ipsilateral limb (–42.9±4.1 mm Hg; mean ± SE); 2. a decrease of the PP in the contralateral limb (–36.4±5.1) and, 3. a fall of the aortic pressure (–14.3±1.5). Similar effects were observed upon stimulation of the peripheral stump of the sectioned ventral roots. These vascular effects were resistant to cholinergic and beta-adrenergic block, but were abolished by hexametonium and by the i.a. administration of antihistamines in doses which did not suppress the vascular reactivity to test doses of acetylcholine and isoproterenol. These experiments suggest the presence in these lower lumbar ventral roots of the preganglionic segment of an histaminergic pathway affecting vascular resistance in the hind limb of the dog.     

Heterogeneity in the response to histamine of isolated dog arteries

Arterial rings were used to evaluate the differences in the effect of histamine (HIS) on canine dorsal pedal (DPA) and coronary arteries. Moreover, the responses of intact coronary arteries (IA) to HIS were compared with those of arteries isolated from sham operated dogs (SA) and from dogs in the late postinfarction period (PA). DPA responded to HIS added cumulatively with contraction which was potentiated by cimetidine (CIM) and reversed by mepyramine (MEP). IA responded with relaxation potentiated by MEP and reversed by CIM. Under resting conditions, coronary arteries responded to a single concentration of HIS with contraction or relaxation (in IA, SA). In PA, only contractions were seen. Responses of PA were significantly higher than those of IA and SA. It appears that in PA the ratio of H₁- and H₂-receptors is changed.     

数字减影血管造影技术在犬下肢动脉造影中的应用

文题释义：数字减影血管造影步进技术：在只注射一次对比剂的情况下,根据不同血流速度和充盈程度,通过控制造影床的移动,进行跟踪造影,一次注射对比剂即可实现全部血管显影;相比于传统的分段造影,可显著减少对比剂用量及曝光时间。动物模型：通过对实验动物进行特定的外部干预,使动物产生某一方面的疾病状态或生理变化,达到对人体特定情况的模拟,从而以此为平台进行反复的观察和研究,以便更准确地观察模型的实验结果并与人类疾病进行比较研究,有助于更方便、更有效地认识人类疾病的发生发展规律,研究防治措施。背景：目前对下肢血管疾病的研究趋于热门,在以大型动物为研究平台的实验中,需要对动物下肢血管进行形态及密度的检测,以研究和验证干预措施的有效性,且这种检测方法需要较高的可行性及可重复性。目的：探讨数字减影血管造影技术应用于犬类动物模型下肢动脉造影中的可行性、影响因素及应用价值。方法：6只比格犬经麻醉后固定于工作床,于犬大腿上段股动脉搏动明显处,采用留置针进行经皮股动脉顺行穿刺,人工推注对比剂,采用数字减影血管造影步进技术采集造影图像,对图像效果及影响因素进行分析。结果与结论：①所有6只比格犬双后肢最终动脉造影图像显示清晰,能分辨细小血管分支,无伪影;②其中第1只犬在初次造影时因对比剂刺激导致肢体抖动,图像效果欠佳,经固定肢体及稀释对比剂后再次造影得到了清晰图像;③提示采用数字减影血管造影技术进行犬类动物模型动脉造影可以清晰显示血管形态及密度,操作简单、重复性好,对模拟肢体缺血的动物模型研究具有重要意义。ORCID: 0000-0003-0335-021X(张世勇)中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程     

Effects of microwave irradiation on blood flow in the dog hindlimb

Physiotherapeutic doses of microwave irradiation to the hindlimb of the anaesthetized dog increased the temperature in the underlying skin and muscle by 5-6 degrees C and, after a latency of 2-8 min, heart rate, blood pressure and femoral conductance all increased. The conductance increase was predominantly in the paw. At this time plasma catecholamine levels were elevated above resting values. At the conclusion of irradiation, heart rate and blood pressure rapidly returned to basal levels, but there was a sustained increase in femoral conductance which was mainly in the leg. The results are discussed in terms of the likely mechanisms underlying the effects of microwave irradiation on limb blood flow and compared with those obtained with direct heating of arterial blood and limb tissue in the accompanying paper.     

Dynamic analysis of an avian drinking response

The drinking response of the water deprived pigeon is analysed by means of feedback theory. The techniques utilized include limiting the rate of water injestion in an operant situation, interrupting the drinking response for a specified interval, and altering the salinity of the drinking water. The results indicate that the drinking response is basically an exponential function of time, the time-constant being determined by the gain of an injestion mechanism, and independent of the absorption constant. The amount of water injested is attenuated as a function of injestion rate, and a thirst-threshold is thought to be responsible for this. The drinking response can be simulated by a second-order feedback mechanism, in which the damping factor is determined by the salinity of the injested water.