Clonidine lowers blood pressure by which mechanism?

Clonidine lowers blood pressure by which mechanism?

• A. Reducing sympathetic outflow from the brain stem
• B. Inhibiting ACE
• C. Blocking calcium channels
• D. Increasing renin production

Answer: (A)

Clonidine lowers blood pressure by dampening central sympathetic nervous system activity. It is a central alpha-2 adrenergic agonist, acting in the brainstem to reduce sympathetic outflow to the heart and vessels. With less sympathetic signaling, norepinephrine release drops, leading to decreased peripheral vascular resistance and a slower heart rate, which together lower blood pressure. This isn’t achieved by inhibiting the ACE enzyme (that would be an ACE inhibitor), nor by blocking voltage-gated calcium channels (that would be a calcium channel blocker). Increasing renin production would typically result from higher sympathetic activity, not from clonidine’s action, since it actually reduces sympathetic tone.

Clonidine lowers blood pressure by dampening central sympathetic nervous system activity. It is a central alpha-2 adrenergic agonist, acting in the brainstem to reduce sympathetic outflow to the heart and vessels. With less sympathetic signaling, norepinephrine release drops, leading to decreased peripheral vascular resistance and a slower heart rate, which together lower blood pressure.

This isn’t achieved by inhibiting the ACE enzyme (that would be an ACE inhibitor), nor by blocking voltage-gated calcium channels (that would be a calcium channel blocker). Increasing renin production would typically result from higher sympathetic activity, not from clonidine’s action, since it actually reduces sympathetic tone.