What evidence suggests that the cardio-protective mechanism of wax apple targets the signaling pathways of the endothelium rather than the smooth muscle cells directly?

Answer

Relaxation responses to sodium nitroprusside (SNP) remained unaffected.

Sodium nitroprusside (SNP) is an endothelium-independent relaxant; since responses to it were not affected, it implies the primary mechanism of action involves the endothelial signaling pathways, not the muscle cells themselves.

What evidence suggests that the cardio-protective mechanism of wax apple targets the signaling pathways of the endothelium rather than the smooth muscle cells directly?
healthfruitbenefitapplemacopa