Disposition and hypoglycaemic action of glipizide in diabetic patients given a single dose of nifedipine

Summary Adrenaline, when administered in dental local anaesthetic solutions, significantly reduces the plasma potassium concentration in young healthy adults. This effect occurs within 10 min of extravascular injections into the maxillary buccal sulcus and may influence the choice of local anaesthetic solution for patients receiving kaliuretic diuretics.     

Factors determining the ability of parents to effectively administer intramuscular adrenaline to food allergic children

Intramuscular adrenaline is the treatment of choice for food-related anaphylactic reactions. Although auto-injectable adrenaline devices are routinely prescribed for patients at risk of serious reactions, previous studies have shown that only one-third to one and a half of patients or their carers are able to properly use these devices. The aim of this study was to determine which factors are most strongly associated with the effective use of these devices. A 122 children with food allergies who had previously been prescribed EpiPens and were attending a single specialist pediatric allergy center in the UK. were studied prospectively. A 69% of parents were unable to use the EpiPen, did not have it available, or did not know when it should be administered. A prior practical demonstration was associated with a 4-5 fold greater chance that parents would be able to use the device (p < 0.005). Prior consultation with an allergy specialist rather than a general physician, and parents who independently sought additional information from the national self-help allergy organization were also four to six times more likely to be competent with these devices (p < 0.005). The study clearly shows that for EpiPens to be used safely and effectively it is essential to educate the carer at the time the device is prescribed.     

达芬霖与肾上腺素在鼻内窥镜手术中应用的比较

目的探讨达芬霖与肾上腺素在鼻内窥镜手术中的应用价值。方法观察达芬霖、肾上腺素分别在鼻内窥镜手术应用中对患者血压、心率的影响,观察出现反跳性鼻腔黏膜充血肿胀的时间和例数,并进行对比讨论。结果在达芬霖应用前后,30例患者的血压、心率变化差异无显著性,在肾上腺素应用前后,30例患者的血压、心率变化差异也无显著性,60例手术均在1￣3h内完成,达芬霖组无1例出现反跳性鼻腔黏膜充血肿胀,肾上腺素组有6例出现轻微的反跳性鼻腔黏膜充血肿胀,达芬霖组平均出血量248mL,肾上腺素组平均出血量120mL,P<0.05。结论达芬霖、肾上腺素作为鼻黏膜血管减充血剂和麻醉辅助药,常规用于鼻内窥镜手术是安全、有效的,用肾上腺素优于用达芬霖。     

华蟾蜍毒素对离体豚鼠输精管的作用

华蟾蜍毒素(华蟾素)使离体豚鼠输精管产生剂量依赖性收缩反应,利血平化豚鼠输精管及冷藏输精管对华蟾素反应减弱。给酚妥拉明、维拉帕米后,输精管对华蟾素反应均受抑制,溴苄胺可使反应潜伏期缩短。结果提示华蟾素收缩输精管反应可能与其促进肾上腺素能神经末稍NA释放有关。     

Activation of the langendorff perfused rat heart depolarized by increased external potassium concentration

Myocardial activation under depolarized conditions was studied in spontaneously beating Langendorff perfused hearts from albino rats. Depolarization was obtained by increasing external potassium concentration in steps (5.4, 7.4, 10, 10.5, 11 and 11.5 mM) in the perfusing solution with or without adrenaline (Adr). Left ventricle isovolumic systolic pressure and coronary flow did not change as external potassium increased, albeit being larger with Adr in the perfusing solution. Atrial and ventricular rates decreased, the latter showing a larger decline. The same behaviour was displayed by perfused hearts, with higher rates being developed by the group with Adr. PR interval and QRS complex duration increased as a function of external potassium. PR intervals were the same in both groups but QRS duration was larger in the Adr group, indicating that AV conduction was not changed in presence of Adr but intraventricular conduction was delayed in that situation. It was also observed that in the great majority of perfused hearts, differing from isolated preparations, ventricular mechanical activity ceased at around 11.5 mM external potassium.     

Variable effects of β-adrenoceptor blockade on muscle blood flow during exercise

The role of β-adrenoceptors in exercise-induced muscle hyperaemia was investigated. Exercise was performed with a small and a large muscle mass: knee extension (KE) and bicycle exercise (BE). Seven healthy subjects performed light and maximal KE and eight subjects performed stepwise dynamic BE to exhaustion before and after acute i.v. administration of propranolol (0.15 mg kg^-1). Leg blood flow was measured by a bolus dye dilution technique. During KE at low and high power leg blood flow was reduced by 8.7 and 10.5% after propranolol was administered, mean arterial blood pressure (MAP) was reduced at low, but not at high power resulting in increased leg vascular resistance (LVR) during high intensity. During BE propranolol reduced leg blood flow and increased LVR at low power, but not at high power. At high BE intensity LVR did not change with increasing power and was slightly decreased after propranolol was administered. In this situation oxygen uptake was close to maximum and the concentration of catecholamines was 3–5 times higher compared with KE. There was no significant effect of propranolol on lactate release or arterial-femoral venous (a-fv) differences for adrenaline or noradrenaline. We conclude that β-adrenoceptors modulate local vasodilation in skeletal muscles during exercise independently of local muscle energy demand, but that the effect is highly dependent on active muscle mass since a-adrenergic activity during maximal BE seemed to disguise any effect of propranolol on LVR.     

No effects of large doses of catecholamines on vascular permeability in isolated blood-perfused dog lungs

Neurogenic pulmonary oedema (NPO) is believed to be induced by intense activation of the sympathetic nervous system, characterized by massive secretion of catecholamines into the blood stream. There is a possibility that NPO is partly the result of increased vascular permeability. However, the mechanism for an increase in pulmonary vascular permeability is not known. The present study was designed to test the hypothesis that large doses of catecholamines increase pulmonary microvascular permeability directly. Adrenaline or noradrenaline (100 and 300 pug) was injected as a bolus into isolated dog lungs perfused with heparinized autologous blood at constant pressure. Adrenaline or noradrenaline produced sustained lung weight loss although both catecholamines increased pulmonary capillary pressure, assessed by double occlusion pressure, by 2–5 mmHg above baseline. Vascular permeability, as measured by the capillary filtration coefficient and the isogravimetric capillary pressure, did not change significantly frombaseline at 30 and 60 min after catecholamine. Finally, the final-to-initial wet lung weight ratio of the catecholamine-treated lungs did not differ from that of saline-injected control lungs. Thus, we conclude that circulating catecholamines, even at supra-physiological doses, do not increase vascular permeability in isolated blood-perfused dog lungs.     

Effect of histamine infusion on circulating methionine-enkephalin and catecholamine concentrations

In 5 normal adult men, histamine was infused i.v. for 5 min at 20 micrograms/kg/h and at 80 micrograms/kg/h on two occasions one week apart. Diastolic blood pressure fell and heart rate, plasma adrenaline and noradrenaline all rose in a dose-dependent manner, but plasma methionine-enkephalin (Met-Enk) concentrations were unchanged. These results indicate that while Met-Enk may be co-stored with catecholamines (CAs) in the adrenal medulla in at least this paradigm, circulating concentrations of CAs may be altered without similar changes in plasma Met-Enk immunoreactivity.