Final answer:
Inhibition of monoamine oxidase (MAO) would be expected to increase the response to stimulation of postganglionic sympathetic nerves by preventing the breakdown of noradrenaline and increasing its availability at the synapse.
Step-by-step explanation:
Which of the following drug actions would be expected to increase the response to stimulation of postganglionic sympathetic nerves? Inhibition of noradrenaline: The correct answer is C) Inhibition of monoamine oxidase (MAO). MAO inhibitors prevent the breakdown of monoamines, including noradrenaline (norepinephrine). Consequently, inhibiting MAO would lead to an increase in the levels of noradrenaline available at the synapse between postganglionic sympathetic nerves and the target organs, thus enhancing sympathetic responses.
Blockade of alpha-adrenergic receptors, enhancement of noradrenaline reuptake, and activation of beta-adrenergic receptors do not produce a direct increase in the response to stimulation of postganglionic sympathetic nerves.