Which of the following is not an effect of nitroglycerin spray?

• A. Freezes the tips of small blood vessels to prevent leakage.
• B. Dilates veins to reduce preload.
• C. Lowers blood pressure.
• D. Relaxes arteries.

Answer: (A)

Nitroglycerin spray works by releasing nitric oxide, which causes relaxation of vascular smooth muscle. This dilation is greatest in veins, so it reduces venous return to the heart (preload). With enough effect on the arteries as well, systemic vascular resistance falls, leading to lower blood pressure. These changes also ease the heart’s workload and oxygen demand, helping relieve chest pain.

The statement about freezing the tips of small blood vessels to prevent leakage isn’t an effect of nitroglycerin; it does not cause vasoconstriction or vessel freezing. The true effects are vein dilation (reducing preload), lowering blood pressure, and some arterial relaxation.