摘要:

SUMMARY1. Oleic acid was used to produce adult respiratory distress syndrome‐like pulmonary micro‐vascular injuries. The resulting injuries have previously indicated involvement of accumulating neutrophils (Hultkvistet al.1988). Activated neutrophils release oxygen free radicals that may be possible to detect in the plasma.2. The dynamics of neutrophils and platelets were studied in the guinea‐pig after oleic acid‐induced injury (0.03 ml/kg per 10 min).3. As an indication of oxygen free radical activity, plasma levels of uric acid and red blood cell (RBC)‐catalase, were analysed.4. Allopurinol (10 mg/kg, i.p.) was given prior to oleic acid infusion to block the production of uric acid.5. The neutropenia, in contrast to the thrombocytopenia seen at 15 min, was significantly inhibited in the allopurinol pretreated group compared with oleic acid and vehicle alone.6. The blood plasma concentration of uric acid was significantly elevated after 15 min from start of experiment. Allopurinol pretreatment significantly reduced the uric acid plasma level.7. The RBC catalase activity did not change with time within or between any groups.8. The results indicate that sequestration of activated neutrophils in the microvasculature are to some extent oxygen free radical

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1991.tb01422.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

SUMMARY1. In rabbit isolated perfused ear arteries denuded of endothelium, a low concentration of endothelin‐1 (0.1 nmol/L) that had no direct vasoconstrictor action produced slowly developing enhancements of vasoconstrictor responses to noradrenaline and sympathetic nerve stimulation. The enhancements reached maximal levels after 60 min of exposure to endothelin‐1.2. A higher concentration of endothelin‐1 (1 nmol/L), which produced a slow‐developing increase in perfusion pressure of 70 mmHg over the course of 1 h, significantly enhanced vasoconstrictor responses to sympathetic nerve stimulation for the first 30 min, after which there was no significant enhancement. Responses to noradrenaline were not enhanced by 1 nmol/L endothelin‐1.3. The enhancing effect of low concentrations of endothelin‐1 on vasoconstrictor responses to sympathetic nerve stimulation and noradrenaline may play a physiological role in modulating vasomot

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1991.tb01423.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

SUMMARY1. Adrenaline was infused intravenously in rats during the clearance from plasma of an injected lipid emulsion designed to model chylomicrons and the triacylglycerol‐rich plasma lipoproteins. The clearance rates of emulsion radiolabelled triolein (TO) and cholesteryl oleate (CO) were both increased, suggesting that hydrolysis of lipoprotein triglycerides and clearance of remnants from plasma were increased. The distribution of radiolabels in tissues showed more TO in skeletal and cardiac muscle after adrenaline, while more CO was found in liver compared with controls. Lesser amounts of both labels were found in the spleens of treated rats.2. In a similar experiment with noradrenaline, the clearance rate of emulsion CO was decreased. The removal of CO was retarded more than that of emulsion TO, which was not significantly affected, and CO label recovered in liver was significantly decreased, suggesting that the removal of remnants from plasma was slowed after noradrenaline. In experiments in which noradrenaline was infused continuously for 1 week the clearances of emulsion CO and TO were both reduced.3. Our findings suggest possible connections between plasma catecholamines and the development of arteriosclerosis, in view of the atherogenicity of remnants of the triacylglycerol‐rich plasma lipoproteins. Yet to be established is whether the linkage we have found between lipoprotein clearance, adrenaline and noradrenaline contributes to the atherogenic effects of chronic stress and for the protective effects of exerc

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1991.tb01424.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

SUMMARY1. In order to further clarify the relationships between parathyroid function and development of hypertension, the effects of parathyroidectomy (PTX) on blood pressure and on responsiveness of atria isolated from spontaneous hypertensive rats (SHR) were examined.2. PTX was carried out in 6‐week‐old SHR and normotensive Wistar rats. The experiments were performed 2 weeks after surgery.3. PTX reduced the plasma calcium concentration and decreased atrial calcium content in SHR. On the other hand, basal contractile force and beat frequency of isolated atria were higher in PTX SHR than in sham‐operated SHR. In response to cumulative addition of isoprenaline, atria from PTX SHR displayed diminished inotropic and chronotropic responses compared with sham‐operated SHR. Similar results were obtained in atria isolated from Wistar rats. When calcium sensitivity was studied in atria from Wistar rats, basal and isoprenaline‐induced maximum contractile forces were higher in PTX group than in the sham‐operated group. Nevertheless, basal and isoprenaline‐induced maximum contractile forces, determined at the respective plasma ionized calcium concentration of PTX and sham‐operated groups (0.83 and 1.22 mmol/L), were not significantly different.4. Our results do not favour a role for alteration in atrial activity as a causal mechanism in delayed development of experimental genetic hypertension after pa

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1991.tb01425.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

SUMMARY1. The role of the sympathetic nervous system in orthostatic and postprandial blood pressure reduction in patients with essential hypertension was studied in 13 hypertensive patients and 10 age‐matched normotensive subjects.2. The blood pressure (BP), pulse rate, and plasma norepinephrine (NE) were measured: (i) every minute for 20 min in the upright position after overnight recumbency (ii) every 30 min after food intake for 3 h in the supine position.3. Orthostatic BP reduction (>13 mmHg in mean BP) was observed in eight hypertensive patients with a maximum after 4 min. Seven of these patients showed postprandial hypotension (>13 mmHg) with a maximum 90 min after eating, while none of the normotensives exhibited such BP reductions. Before and during the tests the plasma NE levels were higher in hypertensive patients than in the normotensives. The plasma NE level was increased from 370±80 to 790±110 pg/mL 4 min after standing (P<0.01) in hypertensive patients and from 220±40 to 530±90 pg/mL (P<0.01) in normotensive subjects. The plasma NE level was decreased 90 min after food intake from 390±90 to 260±80 pg/mL in hypertensives. Changes in plasma NE correlated with those in mean BP after standing for 4 min (r= 0.379,P<0.05) and also with those 90 min after food intake (r= 0.457,P<0.05).4. These findings suggest that patients with essential hypertension have abnormally increased basal sympathetic nerve activity at rest, and that their orthostatic and postprandial BP reductions may both be caused by impairment of the sympathetic nervous system and of cardiovascular r

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1991.tb01426.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

SUMMARY1. For the purpose of clarifying the mechanism of the airways smooth muscle relaxant action of xanthines, cyclic guanosine monophosphate (GMP) phosphodiesterase (PDE) from guinea‐pig trachealis muscle was purified with diethylaminoethyl ether (DEAE) cellulose column chromatography.2. Five 3‐alkylxanthines (3‐methylxanthine, 3‐ethylxanthine, 3‐n‐propylxanthine (enprofylline), 3‐n‐butylxanthine, and 3‐iso‐butylxanthine), and five 1‐methyl‐3‐alkylxanthines (1‐methyl‐3‐methyl‐xanthine (theophylline), 1‐methyl‐3‐ethylxanthine, 1‐methyl‐3‐n‐propylxanthine, 1‐methyl‐3‐n‐butyl‐xanthine, and 1‐methyl‐3‐iso‐butylxanthine (IBMX)) were compared in terms of purified cyclic GMP PDE inhibition. The relationship between the structure and inhibition of cyclic GMP PDE was studied.3. The –log EC50values for relaxation of spontaneous tone of isolated guinea‐pig trachealis preparations by the 3‐alkylxanthines and 1‐methyl‐3‐alkylxanthines were determined.4. The five 1‐methyl‐3‐alkylxanthines were each more potent in relaxing isolated trachealis smooth muscle than the corresponding 3‐alkylxanthines. The 1‐methyl‐3‐alkylxanthines were also more potent than the corresponding 3‐alkylxanthines in their cyclic GMP PDE inhibitory effect. There was a strong positive correlation between the concentration of inhibitor which inhibited hydrolysis by 50% (IC50) values for cyclic GMP PDE inhibition by the xanthine derivatives and their EC50values for trachealis muscle relaxation.5. It is suggested that the mechanism by which xanthine derivatives relax trachealis smooth muscle involves

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1991.tb01427.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

SUMMARY1. The reliability of the Kety‐Schmidt nitrous oxide (N2O) blood–tissue equilibration method was examined in 50 studies of myocardial blood flow in seven conscious, unrestrained sheep using a newly developed carefully validated gas chromatographic assay for N2O.2. In 10 studies the arterial and coronary sinus N2O blood concentration–time curves converged as expected at the end of the 10 min sampling period. In 14 studies they crossed over, and in 26 studies, the curves failed to converge.3. A survey of the literature revealed that such results have been encountered previously but have not been accorded particular significance. An ultimate matching equilibrium between arterial and venous blood N2O concentration–time curves is, however, fundamental to the validity of the method.4. The results indicate that the use of the Kety‐Schmidt method with N2O as the indicator gas is invalid as applied to the measurement of myocardial blood flow in this pr

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1991.tb01428.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

SUMMARY1. The actions of lidocaine on cardiac pacemaker rhythms were studied in anaesthetized dogs and in Purkinje fibres from hearts of the same animals.2.In vivo, lidocaine (1 mg/ kg, intravenously) slowed the sino‐atrial (SA) node rhythm (– 5.0%), and (during vagal stimulation) prolonged ventricular standstill by + 25.1% and slowed the idioventricular rhythm (– 16.7%). A higher dose (4 mg/kg) had more pronounced effects.3. Propranolol also slowed sinus (– 26.2%) and idioventricular (– 27.2%) rhythms, and prolonged ventricular standstill (+ 36.8%). In the presence of propranolol, the effects of lidocaine on idioventricular rhythm were exaggerated.4. In Purkinje fibres drivenin vitro, lidocaine (10 μmol/L) decreased contractile force (– 47.9%) and (during the interruption of drive) prolonged the suppression of (+ 53.2%) and slowed the escape rhythm (– 67.0%).5. In the presence of lidocaine the threshold potential was shifted to less negative values and diastolic depolarization slope was decreased (– 23.6%).6. Lidocaine slowed spontaneously active Purkinje fibres, abolished early afterdepolarizations in low [K]0and slow responses in high [K]0(by shifting the threshold to less negative values), and antagonized strophanthidin arrhythmias.7. TTX reduced the hyperpolarization by lidocaine in low [K]0and vice versa.8. We conclude that lidocaine enhances vagally‐induced ventricular standstill by depressing the idioventricular rhythm far more than the sinus rhythm, an action enhanced by beta‐blockade. Furthermore, lidocaine depresses normal and different types of abnormal automaticity through direct and indirect effects of the blockade of the

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1991.tb01429.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1991.tb01430.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Methodological Errors in Medical Research.By Bjorn Andersen

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1991.tb01431.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY