摘要:

SUMMARY1. In addition to the classical cholinergic bronchoconstrictor and adrenergic bronchodilator neural mechanisms, there is a large volume of evidence to suggest the existence of neural pathways within the airways of a variety of species which are neither adrenergic nor cholinergic, the non‐adrenergic, non‐cholinergic (NANC) mechanisms. With respect to airway smooth muscle tone, NANC neural responses may induce either contraction (excitatory, e‐NANC) or relaxation (inhibitory, i‐NANC). Early investigations of NANC mechanisms in both human and other animal airways suggested a role for neuropeptides as the putative neurotransmitters.2. Excitatory NANC (e‐NANC) bronchoconstrictor responses are believed to be mediated by the release of sensory neuropeptides from a subpopulation of non‐myelinated C‐fibre primary afferent neurones in the airways. e‐NANC nerves, which release tachykinins such as substance P (SP), neurokinin A (NKA) and the peptide calcitonin gene‐related peptide (CGRP, produced as a result of alternative splicing of the calcitonin gene) are selectively degenerated by the nerve toxin capsaicin (an extract from hot peppers), with the subsequent abolition of the e‐NANC responses. Tachykinin receptors have been detected by radio‐ligand receptor binding studies and visualized by autoradiographic mapping, and exogenous addition of these peptides elicits a bronchoconstrictor response in both human and other animal airways. In addition to these effects on airway smooth muscle tone, tachykinins produce an increase in microvascular permeability (and associated oedema formation), mucus hypersecretion and cause an exaggerated cholinergic bronchoconstrictor response. Thus, tachykinins may play a role in the inflammatory process and contribute to the neurogenic inflammation as seen in asthma.3. Inhibitory NANC (i‐NANC) bronchodilator responses were believed to be due to the release of peptides such as vasoactive intestinal peptide (VIP) and peptide histidine isoleucine/methionine (PHI/M). VIP is believed to be co‐localized to cholinergic nerves in the airways and is co‐released upon cholinergic nerve stimulation. Recent evidence, however, would suggest that, together with VIP and related peptides, another substance may mediate i‐NANC responses in the airways. Nitric oxide (NO), which is formed from arginine in a reaction catalysed by the enzyme NO synthase, has been shown to mediate bronchodilator responses evoked in both human and other animal airway smooth muscles following nerve stimulationin vitro.4. NANC neural mechanisms play an important role in the maintenance and regulation of bronchomotor tone, either via the direct effects of the transmitters released or by neuromodulation of autonomic control mechanisms. The study of NANC nerves in the airways has led to a greater understanding of the interaction between different nerve types in the respiratory tract and provided new insights into, and understanding of, the p

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1991.tb01380.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

SUMMARY1. To obtain information on regulation of the brain renin–angiotensin system, the effect of long‐term administration of angiotensin‐converting enzyme (ACE) inhibitor on brain renin and angiotensinogen mRNA was studied.2. Spirapril (3 mg/kg) was orally administered daily for 8 weeks to spontaneously hypertensive rats (SHR) from 12 weeks after birth. Renin and angiotensinogen mRNA in the brain and kidney were then quantitated by Northern blot analyses with [32P]‐labelled rat renin and angiotensinogen cDNA as hybridization probes. Plasma renin activity (PRA), angiotensin II (AII) concentration, plasma ACE activity and brain tissue ACE activity were also measured.3. Compared with the control group, the Spirapril‐treated group had significantly lower blood pressure (P<0.01), significantly higher PRA (P<0.01), a not significantly different plasma AII concentration, and lower plasma and brain ACE activities (P<0.01). Interestingly, the brain renin and angiotensinogen mRNA levels of the two groups were similar, but the renal renin mRNA level was significantly higher in the Spirapril‐treated group (P<0.01).4. These results indicate that the mRNA levels of brain renin and angiotensinogen were not affected by chronic ACE inhibition in the circulation and suggest that AII in the brain might not be affected by systemic ACE

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1991.tb01381.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

SUMMARY1. The anticonvulsant effects of subanaesthetic doses of propofol and thiopentone against PTZ‐induced seizures and mortality were examined in the rat.2. Administration of propofol (50 mg/kg, i.p.) 5 min prior to PTZ treatment increased the 2 h CD50 and the 24 h LD50 of PTZ by 3.4‐fold, whereas thiopentone pretreatment (20 mg/kg, i.p.) increased these values by more than five‐fold.3. Both propofol and thiopentone prolonged the latency to the onset of clonic seizure but the effects of the former were more marked.4. The data demonstrate that propofol was more effective than thiopentone in providing complete protection against PTZ‐induced seizures for the first 30–40 min of observation and that thiopentone, because of its sustained effects, was more effective in reducing the cumulative incidence of seizures and mortality over 2 and 24 h, respectively.5. We conclude that propofol is a very effective anticonvulsant and provides complete protection of short duration against PTZ‐induced seizures

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1991.tb01382.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

SUMMARY1. Total plasma cholesterol, high‐density lipoprotein cholesterol (HDL‐C), low density lipoprotein cholesterol (LDL‐C), noradrenaline, haematocrit, haemoglobin and heart rate were measured in blood sampled from an antecubital vein in nine volunteers after 1 min standing and at intervals up to 1 h following 5 min of vigorous bicycle exercise.2. Heart rates and plasma noradrenaline levels rose substantially immediately following exercise and gradually returned toward baseline levels 60 min post‐exercise.3. Total plasma cholesterol levels rose by 24% immediately post‐exercise and slowly returned to baseline levels 60 min post‐exercise. Similar changes were observed for LDL‐C (20.2%) and HDL‐C (27.7%). As a result, LDL:HDL ratios did not alter.4. These changes in total plasma cholesterol, HDL‐C and LDL‐C were explained by changes in plasma volume that occurred as a consequence of vigorous exercise.5. Changes in plasma volume may be a mechanism by which some environmental factors such as stress are associated with elevated plasma

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1991.tb01383.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

SUMMARY1. Mice were swum for 3 min at room temperature.2. After this stress ‘sleeping time’ in response to pentobarbitone was increased by over 70%.3. Loss of ‘righting reflex’ occurred in these stressed animals at brain concentrations of pentobarbitone which were 40% lower than those needed for ‘sleep’ in the unstressed mice, indicating a true increase in sensitivity to the drug. ‘Waking’ (the return of the righting reflex) occurred at identical levels in both groups.4. Kinetic analysis showed that the rates of absorption, elimination and transfer between plasma and brain were slower in the swum than in the unswum mice, probably because of the reduced body temperatures produced

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1991.tb01384.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

SUMMARY1. The fluctuations that underlie the spontaneous variability of blood pressure (BP) and heart rate (HR) were investigated in conscious normotensive rats using power spectral analysis.2. Air jet stimulation determined a significant BP rise associated with a tachycardia. This environmental mild stressor amplified the 195–605 mHz oscillations of HR which are under autonomic control. No habituation to this stressor was observed since a second stimulation determined similar responses.3. Clonidine (10 μg/kg, i.v.) prevented the BP rise normally associated with air jet stimulation. In addition, clonidine dramatically reduced the amplitude of BP and HR oscillations in the frequency region of 195–605 mHz.4. It is concluded that a mild emotional stressor elicits in normotensive rats a rise in BP and HR associated with modified spectral profiles reflecting sympathetic hyperactivity. Clonidine minored the effects of stress on BP and HR variability and also prevented BP eleva

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1991.tb01385.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

SUMMARY1. Adult soft‐shelled turtles were exposed to hyperosmotic and dehydration stresses.2. Acute treatment for 0.5, 1 or 2 h with sodium chloride (3.6%, single intramuscular injection, 2 mL volume) caused depletion of pineal serotonin contents followed by elevation of norepinephrine and epinephrine levels. In addition, it depleted corticosterone and norepinephrine from the adrenal gland.3. The serotonin level also decreased with a concomitant increase of 5‐hydroxyindoleacetic acid but without any discernible change in catecholamine content after chronic treatment with sodium chloride (3.6%, 0.5 mL daily for 7 days).4. Dehydration for 7 days brought about depletion of serotonin and epinephrine levels and elevation of norepinephrine level.5. The findings suggest that hyperosmotic stress has a definite influence on pineal‐paraphyseal serotonin, 5‐hydroxyindoleacetic acid, norepinephrine and epinephrine concentrations, and adrenal corticosterone and norepinephrine contents inLissemysturtles. Dehydration stress also modulates pineal‐paraphyseal serotonin, norepinephrine and epinephrine conce

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1991.tb01386.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

SUMMARY1. The aim of the present study was to determine the effect of water restriction and/or hypoxia on the vasopressin response to haemorrhage in conscious rats.2. Male, Long‐Evans rats (n= 39) were prepared with chronically indwelling femoral artery and vein catheters and exposed to 24 h of one of the following: normoxia withad libdrinking water (N + W); normoxia with water restriction (N – W); hypoxia withad libdrinking water (H + W); and hypoxia with water restriction (H – W). At the end of 24 h, a 15 mL/kg arterial haemorrhage was performed.3. Water restricted rats had elevated pre‐haemorrhage vasopressin levels. Haemorrhage induced an increase in vasopressin in all groups. Water restriction (N – W) or hypoxia (H + W) each augmented the vasopressin response to haemorrhage. However, the combination of hypoxia and water restriction (H – W) failed to augment the vasopressin response to haemorrhage as compared to normoxic, water replete (N + W) rats.4. Hypoxia or water restrictionper seaugment the vasopressin response to haemorrhage. This augmented vasopressin response to haemorrhage is not maintained when hypoxia and water restriction a

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1991.tb01387.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.tb01388.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The Biology and Clinical Applications of hterleukin‐ 2. Edited by R. C. Rees. IRL Press at Oxford University Press, 1990. Illustrated, pages xvii + 181. Price: $59.50Receptor Biochemistry: A Practical Approach. Edited by E. C. Hulme, Oxford University Press, Oxford, UK, 1990. Illustrated, pages 323. Price: $62.

ISSN:0305-1870    

DOI:10.1111/j.1440-1681.1991.tb01389.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY