Effects of propofol on isolated human pial arteries

BACKGROUND: The intravenous anaesthetic propofol has been reported to increase cerebral vascular resistance in vivo. The underlying mechanisms are not fully understood, but may include effects on metabolism and direct effects on the vascular smooth muscle. The present study was designed to evaluate the direct effects of propofol on human pial arteries. METHODS: We investigated the direct effect of propofol (10(-6)-10(-4) M) on isolated human pial arteries at basal tension as well as the influence on contractions induced by 5-hydroxytryptamine, prostaglandin F2alpha, noradrenaline and potassium chloride. RESULTS: Propofol did not change the basal tension. Propofol at 10(-6) and 10(-5) M did not affect the concentration-response curves of any of the contractile agents tested. Propofol at the supraclinical concentration 10(-4) M reduced the contractions induced by all contractile agents. CONCLUSION: Propofol reduces the tone of human pial arteries in vitro at supraclinical concentrations, but has no effect on the tone at clinically relevant concentrations.     

Aortopulmonary collateral artery embolization during postoperative extracorporeal membrane oxygenation after arterial switch procedure

Aortopulmonary collateral arteries sometimes complicate cyanotic congenital heart defects. Combined with a relevant left-right shunt, this could result in massive airway bleeding during and after corrective surgery. A preoperatively diagnosed 1.2 mm small aortopulmonary collateral artery in a newborn suffering from transposition of the great arteries caused life-threatening airway bleeding during surgery. Postoperative extracorporeal membrane oxygenation (ECMO) was necessary, and coil embolization was performed on ECMO to terminate pulmonary bleeding.     

颈总动脉形态及血流动力学改变与脑梗死类型的关系

目的研究颈总动脉形态及血流动力学改变与脑梗死类型的关系。方法应用经颅彩色双功能多普勒超声检查法．测定40例脑穿通支动脉梗死、31例脑主干支动脉校死和30例正常对照者的颈总动脉管径及有或无粥样斑块等反映血管形态和收缩峰速、每分钟血流量、阻力指数等血流动力学指标。结果结果表明当颈总动脉出现粥样斑块,而无明显血流动力学改变时,易发生穿通支脑梗死;随着血流动力学,尤其是血流收缩峰速度和阻力指数等指标的异常程度加重,发生脑主干动脉梗死的危险性增大。结论颈总动脉形态及血流动力学改变与患者发生脑梗死类型密切相关。     

妊高征患者胎儿脐血流速度与围产儿预后的关系

目的：探讨妊高征患者胎儿脐动脉血流速度比值（Ｓ／Ｄ）与围产儿预后的关系,方法：应用彩色超声波对９８例妊高征患者胎儿脐动脉血流速度指数进行测量并与新生儿体重,新生儿Ａｐｇａｒ评分,羊水性质和围产期结局的关系进行分析,结果：９８例妊高征中有３４例围产儿预后良好,６４例围产儿预后不良,围产儿预后不良发生率,中,重度妊高征明显高于轻度妊高征（Ｐ〈０．０１）,Ｓ／Ｄ比值与围产儿预后的程度业的相关性,结论,产     

Contractile effect of big endothelin-1 and its conversion to endothelin-1 in rabbit cerebral arteries

The effect of big endothelin-1 (big ET-1) and its conversion to endothelin-1 (ET-1) in rabbit cerebral arteries were examined. Big ET-1 and ET-1 induced concentration-dependent contractions in the basilar artery; ET-1 was approximately 8 times more potent than big ET-1. The metalloprotease inhibitor phosphoramidon (30 ol/1) almost abolished the contractile response to big ET-1, whereas the ET-1-induced contraction was unaffected. Removal of the endothelium did not attenuate the big ET-1-induced contraction. ET-1 was approximately 14 times more potent than endothelin-3 (ET-3) to elicit contraction. The contractions induced by big ET-1, ET-1 and ET-3 were all inhibited by the ET_A receptor antagonist BQ 123 (3 mol/l). The ET_B receptor antagonist IRL 1038 (3 mol/l) had no effect on the contractile responses to big ET-1 and ET 1, but produced a small inhibition of the ET-3-induced contraction. Formation of ET-1 was demonstrated in membrane fractions of cerebral arteries incubated with big ET-1 as measured by high pressure liquid chromatography followed by radioimmunoassay. These results suggest that externally applied big ET-1 is converted to ET-1 by a phosphoramidon-sensitive endothelin converting enzyme present in the vascular smooth muscle cells. The ET-1 formed subsequently mediates the big ET-1-induced contraction by activation of mainly ETA receptors, although a small contribution of ETB receptors cannot be excluded.     

Proceedings of the Symposium ‘Angiotensin AT1 Receptors: From Molecular Physiology to Therapeutics’: STRUCTURAL CHANGES IN THE RENAL VASCULATURE IN THE SPONTANEOUSLY HYPERTENSIVE RAT: NO EFFECT OF ANGIOTENSIN II BLOCKADE

• 1 There is strong evidence for a renal basis to the development of hypertension in the spontaneously hypertensive rat (SHR). Alterations of the SHR renal vasculature, including the glomerulus, may be involved in the initiation and maintenance of hypertension in this animal model.
• 2 The arterial walls of pre-glomerular vessels of the SHR are hypertrophied compared with WKY vessels. Unlike other vascular beds in the SHR, this hypertrophy is independent of angiotensin II (AngII).
• 3 Glomerular number and volume are similar between SHR and the normotensive Wistar-Kyoto (WKY) rats. These results provide no support for the theory that a reduced filtration surface area within the kidneys of the SHR contributes to the elevated blood pressure in these animals.
• 4 Intrarenal hypertrophy may have similar haemodynamic consequences to clipping of the main renal artery, as in Goldblatt hypertension. Further analysis of the role of pre-glomerular arterial hypertrophy is warranted to determine its involvement in the initiation and maintenance of hypertension in the SHR.

     

Patterns of the coronary artery irrigation in the left ventricle

Summary Nowadays, the classifications of coronary arterial preponderance (Schlesinger, Baroldi, Gensini) do not provide the necessary information for a good systematization of coronary arterial irrigation. Based on segmental analysis (Selvester's method) an alternative classification of the arterial distribution of the left ventricle is presented. One thousand eighty ventricle segments corresponding to 90 human hearts (age range from 4 days to 94 years) are studied, using microdissection techniques. In order to obtain segmental arterial patterns, a cluster analysis was used. The alternative classification is based on the predominance of the segments irrigated by: the anterior interventricular artery (Type I; 31% of cases), the circumflex artery (Type II; 37% of cases), or a balance between both arteries (Type III; 32% of cases). Each group can be divided into two subgroups (A and B), according to the existence or not of a balance between the territories of anterior interventricular and circumflex arteries. This classification allows as a more realistic approach to the subject of arterial dominance, given that the left ventricle always presents a predominant irrigation from the anterior interventricular, the circumflex or both arteries.

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Essai de classification de l'irrigation artérielle coronaire du ventricule gauche

Résumé La classification en dominance artérielle coronaire, actuellement utilisée (Schlesinger, Baroldi, Gensini) ne donne pas toutes les informations nécessaires à une bonne systématisation de la distribution des artères coronaires. Nous présentons ici une classification alternative, basée sur la segmentation des parois du ventricule gauche à la manière de Selvester. 1080 segments ventriculaires gauches de 90 coeurs humains prélevés sur des sujets de 4 jours à 94 ans ont été analysés en utilisant les techniques de microdissection. La présente classification est basée sur — la prédominance de segments irrigués par l'artère interventriculaire antérieure (IVA) : type I, par l'artère circonflexe (CX) : type II, — ou sur l'existence d'un équilibre entre ces deux artères : type III. Le pourcentage de distribution de ces groupes est le suivant : type I : 31 % ; type II : 37 % ; type III : 32 %. Chacun de ces groupes peut-être divisé en deux sous-groupes A et B selon — la prédominance du nombre de segments irrigués exclusivement ou en partage par l'IVA, — ou l'existence d'un équilibre entre l'IVA et la CX. Cette classification permet une approche plus réaliste du problème de dominance artérielle, étant donné que le ventricule gauche est toujours irrigué en prédominance par l'IVA, par la CX ou à la fois par les deux.

     

Tissue specific susceptibility of alpha-adrenoceptor mediated vasoconstriction to nifedipine

Summary The influence of the calcium antagonist nifedipine on ₁- and ₁-adrenoceptor vasoconstrictor effects was investigated in vitro. Changes in tension were monitored isometrically on helical strips of canine circumflex coronary and saphenous arteries suspended in 10 ml organ baths and of saphenous veins superfused with Krebs-Henseleit solution. Distinction between ₁- and ₂-adrenoceptor was made by using selective -adrenoceptor blocking drugs such as rauwolscine, yohimbine, corynanthine and prazosin, and the agonists noradrenaline, phenylephrine and guanfacine. In venous and both arterial vascular smooth muscles, the contractile process could be triggered by stimulation of both ₁- and ₂-like adrenoceptors. Nifedipine inhibited the venoconstrictor response to the ₂-agonist guanfacine, leaving that to the ₁-agonist phenylephrine unchanged. In saphenous arteries, nifedipine in addition to guanfacine also antagonized constrictor responses to phenylephrine, though to a significantly weaker extent. In circumflex coronary arteries, nifedipine was equally potent in antagonizing responses to both ₁- and ₂-adrenoceptor stimulation.It is suggested that the susceptibility of -adrenoceptormediated vasoconstrictor effects to blockade by calcium antagonists depends not only on the subtype of -adrenoceptor but, in addition, on the type and origin of vascular smooth muscle and may be a reflection of tissue variations in intracellular calcium stores.     

Presynaptic muscarinic receptor subtypes involved in the inhibition of acetylcholine and noradrenaline release in bovine cerebral arteries

Summary Experiments were performed in bovine cerebral arteries preincubated with [³H]-choline or [³H]-noradrenaline to analyze the presynaptic muscarinic receptors involved in inhibition of acetylcholine and noradrenaline release induced by electrical stimulation (4 Hz, 200 mA, 0.3 ms, 1 min). For this purpose, the actions of several muscarinic receptor antagonists on the ³H overflow and on the carbacol-induced inhibition of this overflow were assessed. The evoked [³H]-acetylcholine release and [³H]-noradrenaline release were markedly reduced by the presence of tetrodotoxin, Ca²⁺-free medium, and the inhibitor of both choline transport and choline acetyltransferase, AF64A. Chemical sympathetic denervation with 6-hydroxydopamine (6-OHDA) decreased the uptake of[³H]-noradrenaline, and AF64A reduced mainly the uptake of [³H]-choline, but also of [³H]-noradrenaline. Carbachol reduced the evoked [³H]-noradrenaline and [³H]-acetylcholine release; the IC₅₀ values were 0.37 and 0.43 mol/l, respectively.Atropine and 4-DAMP, but not AF DX 116, methoctramine or pirenzepine, increased the evoked [³H]-acetylcholine release. However, these muscarinic antagonists failed to modify the evoked [³H]-noradrenaline release. Carbachol inhibited the release of both acetylcholine and noradrenaline. The inhibition was blocked by the antagonists. The rank orders of potency (based on plC₅₀ values) were, in the case of [³H]-acetylcholine release, atropine > 4-DAMP >AF-DX 116 >- pirenzepine >- methoctramine, and, in the case of [³H]-noradrenaline release, atropine > 4-DAMP > AF-DX 116 >- methoctramine >-pirenzepine. These results suggest (1) that the prosynaptic receptors that modulate endogenous acetylcholine release are likely of the M₃ subtype, whilst those involved on the effect of the exogenous agonist Carbachol are of M₂ subtype, and (2) that those which inhibit noradrenaline release are probably a mixture of M₂ and M₃ subtypes as well. The autoinhibition of the acetylcholine release was funtionally active under our experimental conditions, while noradrenaline release does not appear to be modulated by muscarinic receptors in physiological conditions.Send offprint requests to G. Balfagón at the above address     

颈动脉斑块与心脑血管阻塞性疾病关系的临床探讨

目的 探讨颈动脉斑块与心脑阻塞性疾病及视网膜中央动脉阻塞(CRAO)的关系。方法 1995年10月至2002年7月采用彩色多普勒超声对我院心脑血管疾病患者149例行颈动脉检查。结果 检出颈动脉斑块者74例，未检出斑块者75例。有斑块者较无斑块者颈动脉内膜中层厚度明显增加(P＜0．01)。结论 颈动脉斑块严重程度的增加，其内膜中层厚度亦呈增厚趋势。前者是造成脏器梗死的重要原因之一。颈动脉斑块的检测和治疗可作为心脑血管及CRAO疾病的重要预防措施。