Beta‐adrenoceptor responses to inhaled salbutamol in the elderly

The purpose of the present study was to evaluate and compare the responsiveness of beta 2‐adrenoceptors in elderly and young subjects. Seven healthy elderly volunteers (72 +/‐ 3 years) were given cumulative doses of inhaled salbutamol (100 micrograms‐4000 micrograms) or placebo, following pre‐treatment with propranolol 40 mg or placebo. Finger tremor (Tr), plasma potassium (K), and heart rate (HR) were measured at each dose step. There were dose‐dependent increases in Tr (P less than 0.001) and HR (P less than 0.001) and falls in K (P less than 0.001), which were completely attenuated by propranolol (P less than 0.001). Comparison with dose‐response curves in a group of young (Y) subjects (24 +/‐ 3 years) given an identical dose protocol of salbutamol showed no evidence of subsensitivity of beta 2‐adrenoceptor responses in the elderly (E) group (mean and 95% confidence intervals for maximum responses): delta K −0.90 (‐1.1(‐)−0.82) mmol l‐1 Y, −0.82 (‐1.04(‐)‐0.60) mmol l‐1 E, delta Tr 274 (213‐335)% Y, 269 (197‐342)% E, delta HR 25 (21‐28) beats min‐1 Y, 26 (21‐31) beats min‐1 E.