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.