Objective-To assess the benefit of nebulised amiloride added to the standard inpatient treatment of a respiratory exacerbation in cystic fibrosis. Design-Prospective, randomised, double blind, placebo controlled trial. Subjects-27 cystic fibrosis patients (mean age 12'8 years). Setting-Two hospitals in Leeds, UK. Results-Both forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) showed improvements over the course of treatment, although there was no difference in respiratory function between the two groups at any of three time periods during the study. The time to reach peak FVC was significantly reduced in the amiloride group (4-2 v 7-6 days; 95% CI 04 to 6-4 days), but not in the time to reach peak FEV1 (5.7 v 7 9 days; 950/* CI -1*2 to 5 6 days). Conclusions-Amiloride did not result in a greater overall improvement in respiratory function. There was a suggestion that it may have an effect on the rate of improvement, and thus may possibly influence the duration of treatment. This hypothesis deserves fiurther evaluation. (Arch Dis Child 1995; 73: 427-430)

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1 To examine the influence of age on beta‐adrenergic receptor mechanisms, we have observed the cardiovascular, bronchial and metabolic effects of an intravenous infusion of the beta‐adrenoceptor agonist terbutaline in healthy young and elderly female subjects (mean ages 20.9 and 72.1 years respectively). 2 There was a highly significant fall in systolic blood pressure in the elderly, in contrast to the rise in systolic pressure seen in the young subjects. A similar fall in diastolic pressure occurred in both groups, indicating comparable beta‐adrenoceptor‐mediated vasodilatation. The fall in mean arterial pressure was significantly greater in the old than in the young subjects. The increase in heart rate was significantly less in the elderly. 3 Changes in plasma glucose and potassium during the infusion were similar in the two groups. 4 The observed abnormality of myocardial sensitivity to beta‐adrenergic receptor stimulation, which is not associated with a generalized blunting of beta‐adrenoceptor mediated effects, may significantly impair autonomic cardiovascular regulation in the elderly.

Terbutaline is a selective beta 2 agonist used predominantly in the treatment of asthma. Since beta-mediated responses increase heart rate, dilate peripheral arteries, modify carbohydrate metabolism and the uptake of electrolytes into cells, the administration of terbutaline might be expected to produce widespread effects. In this study the intravenous administration of 0.5 mg terbutaline over 60 min has been shown to produce marked changes without upsetting the volunteers. Heart rate, systolic blood pressure and plasma glucose all increase; diastolic pressure and serum potassium decrease. The data suggests that the terbutaline infusion may be a useful tool for the investigator. The results also quantitate some of the side effects which may result from the intravenous administration of a therapeutic dose of terbutaline given to asthmatics or to pregnant women to reduce uterine activity and delay childbirth.

A serial study of erythrocyte deformability, plasma viscosity, and whole-blood viscosity has been made during 10 sickle-cell vaso-occlusive crises. The peak serum lactate dehydrogenase level was used to confirm the duration of crisis and the rheological changes were compared with 19 estimations made on the same patients when asymptomatic. Erythrocyte deformability, measured by filtration of washed erythrocytes through polycarbonate filters of 5 microgram pore size, was significantly reduced on day 1 of crisis and, in one additional patient, this occurred 24 h before the onset of pain. There was no increase in irreversibly-sick-led-cell counts and plasma- and blood-viscosity did not increase significantly until day 5 of crisis, in parallel with the acute-phase rise in plasma fibrinogen. Measurement of erythrocyte filterability is therefore a valuable technique for investigating the pathogenesis of the early stages of sickle-cell crisis.