Clinical and experimental pharmacology & physiology
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Clin. Exp. Pharmacol. Physiol. · Nov 2001
Increased cerebral blood flow and cardiac output following cerebral arterial air embolism in sheep.
1. The effects of cerebral arterial gas embolism on cerebral blood flow and systemic cardiovascular parameters were assessed in anaesthetized sheep. 2. Six sheep received a 2.5 mL injection of air simultaneously into each common carotid artery over 5 s. ⋯ Mean arterial blood pressure, heart rate and end-tidal carbon dioxide were not significantly altered by the intracarotid injection of air. 4. The increased cardiac output is a pathological response to impact of arterial air bubbles on the brain, possibly the brainstem. The increased cerebral blood flow is probably the result of the increased cardiac output and dilation of cerebral resistance vessels caused by the passage of air bubbles.
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Clin. Exp. Pharmacol. Physiol. · May 2001
Randomized Controlled Trial Comparative Study Clinical TrialComparison of digoxin versus low-dose amiodarone for ventricular rate control in patients with chronic atrial fibrillation.
1. Rapid ventricular rate (VR) and rhythm irregularity during atrial fibrillation (AF) impair cardiac performance. Although digoxin has been widely used in patients with AF, its efficacy for the control of VR and rhythm irregularity is unsatisfactory. ⋯ Quality of life, determined by SF-36 questionnaire, and AF symptomatology, as measured by the AF Symptom Checklist, were also not significantly changed after treatment with digoxin or amiodarone (all P > 0.05). 6. In conclusion, digoxin and low-dose amiodarone had similar efficacy in the control of VR during ambulatory activity and exercise. However, both were less efficacious during exercise and did not significantly affect rhythm irregularity, exercise capacity, quality of life and AF symptomatology in patients with chronic AF.
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Clin. Exp. Pharmacol. Physiol. · Mar 2001
ReviewRole of human airway smooth muscle in altered extracellular matrix production in asthma.
1. The underlying abnormality in asthma is not fully understood; however, inflammation, airway remodelling and bronchial hyperresponsiveness are key factors. The plasma exudate from the microvascular leakage plays a significant role in remodelling, which includes extracellular matrix (ECM) protein deposition/breakdown and airway smooth muscle (ASM) hyperplasia/hypertrophy. 2. ⋯ The role of current asthma treatments in the prevention or reversal of airway ECM changes is an area that has only recently become of interest, with the majority of the in vivo work focusing on the effects of corticosteroids. 7. The evidence presented in this review indicates that the ASM may influence its own environment/proliferation through the production of ECM proteins, MMP and TIMP. Further studies are needed to fully understand the role of the ASM in the production of ECM proteins, MMP and TIMP andtheir potential influence in the mechanisms underlying asthma.
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Clin. Exp. Pharmacol. Physiol. · Oct 2000
Cardioprotective effects of nicorandil in rabbits anaesthetized with halothane: potentiation of ischaemic preconditioning via KATP channels.
1. The roles of ATP-sensitive K+ channels (KATP channels) in ischaemic or pharmacological preconditioning in the rabbit heart remain unclear. Infarct limitation by ischaemic preconditioning was abolished by the KATP channel blocker glibenclamide under ketamine/xylazine anaesthesia, but not under anaesthesia induced by pentobarbital. ⋯ Thus, nicorandil alone did not have an infarct size-limiting effect in halothane-anaesthetized rabbits. However, the results suggest that even when nicorandil alone does not demonstrate a direct cardioprotective effect, it may enhance ischaemic preconditioning via KATP channels. Key words: ATP-sensitive K+ (KATP) channel, ischaemic preconditioning, myocardial infarction, nicorandil, rabbit.
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Clin. Exp. Pharmacol. Physiol. · Aug 2000
Clinical TrialRelative timing of inspiration and expiration affects respiratory sinus arrhythmia.
1. The effect of a variation in inspiration and expiration times on heart rate variability was studied in 12 healthy subjects (mean age 30+/-6 years; five females). 2. Two 2 min trials of controlled breathing, with either short inspiration followed by long expiration or long inspiration followed by short expiration, were compared. ⋯ The higher RSA during fast/slow respiration is primarily due to a more pronounced phasic heart rate increase during inspiration, indicating that inspiratory vagal blockade is sensitive to the steepness of inspiration. 4. Respiration rate and tidal volume are respiratory variables known to modulate RSA. The results of the present study indicate that RSA can also be modulated by a third respiratory variable, the expiratory/inspiratory time ratio.