RESUMO
To evaluate the acute effects of insulin on airway reactivity and the protective effects of beclomethasone and ipratropium against insulin-induced airway hyperresponsiveness on isolated tracheal smooth muscle in a guinea pig model. Materials and The trachea of each guinea pig was excised; one end of the tracheal strip was attached to the hook of the oxygen tube of a tissue bath and the other end was connected to a research-grade isometric force displacement transducer. The effects of varying concentrations of insulin [10[-7] to 10[-3]M] and insulin pretreated with a fixed concentration of beclomethasone [10[-6]M] and ipratropium [10[-6]M] on the isolated tracheal tissue were studied by constructing cumulative concentration-response curves. Changes in tracheal smooth muscle contractions were recorded on a 4-channel oscillograph. The means +/- standard error of the mean of the maximum amplitude of contraction with increasing concentrations of insulin and of insulin pretreated with fixed concentrations of beclomethasone and ipratropium were 35 +/- 1.13, 22 +/- 1.15 and 27.8 +/- 1.27 mm, respectively. The data showed that beclomethasone inhibited the contractile response of insulin to a greater extent than ipratropium. Thus we suggest that inhalational insulin pretreated with beclomethasone may be more efficacious than with ipratropium for the amelioration of potential respiratory adverse effects such as bronchoconstriction
RESUMO
Inhalational insulin was withdrawn from the market due to its potential to produce airway hyper-reactivity and bronchoconstriction. So the present study was designed to explore the acute effects of insulin on airway reactivity of guinea pigs and protective effects of salbutamol and beclomethasone against insulin induced airway hyper-responsiveness on isolated tracheal smooth muscle of guinea pig. Effects of varying concentrations of insulin [10[-7] to 10[-3] M], insulin pretreated with fixed concentration of salbutamol [10[-7] M] and beclomethasone [10[-6] M] were studied on isolated tracheal tissue of guinea pig by constructing cumulative concentration response curves. Changes in tracheal smooth muscle contractions were recorded on four channel oscillograph. The mean +/- SEM of maximum amplitudes of contraction with increasing concentrations of insulin, insulin pretreated with fixed concentration of salbutamol and beclomethasone were 35 +/- 1.13 mm, 14.55 +/- 0.62 mm and 22 +/- 1.154 mm respectively. Although salbutamol and beclomethasone both had a profound inhibitory effect on insulin induced airway hyper-reactivity, yet salbutamol is more efficacious than beclomethasone. So we suggest that pretreatment of inhaled insulin with salbutamol may be preferred over beclomethasone in amelioration of its potential respiratory adverse effects such as bronchoconstriction