Advancing age was associated with a progressive decrease in sensitivity to both isoproterenol and propranolol, indicating diminished beta-adrenoceptor responsiveness.
Observational (n=27)
Does advancing age reduce beta-adrenoceptor sensitivity to isoproterenol and propranolol in male volunteers?
Beta-adrenoceptor responsiveness to both agonist and antagonist drugs diminishes progressively with advancing age.
The effect of age on sensitivity to both isoproterenol and propranolol has been investigated in 27 male volunteers aged 21 to 73 yr. The dose of isoproterenol (given as a rapid intravenous injection) required to increase the resting heart rate by 25 bpm (I25) increased with age. The I25 was repeated during an intravenous infusion of propranolol and the dose ratio (I25 after propranolol divided by the control I25) determined. This was related to the concentration of free propranolol in plasma. It was found that the effectiveness of any given free concentration diminished progressively with age. These data are consistent with a diminished responsiveness of the beta-adrenoceptor to both agonist and antagonist drugs with advancing years.
Vestal et al. (Wed,) reported a observational. Advancing age vs. Younger age was evaluated on Sensitivity to isoproterenol (I25) and propranolol. Advancing age was associated with a progressive decrease in sensitivity to both isoproterenol and propranolol, indicating diminished beta-adrenoceptor responsiveness.