A Paracrine Signal That Relaxes Smooth Muscle Cells Is

Question

A paracrine signal that relaxes smooth muscle cells is
A) nitric oxide.
B) vitamin D.
C) testosterone.
D) cortisol.
E) antidiuretic hormone.

Accepted Answer

Nitric oxide is a paracrine signal that relaxes smooth muscle cells by stimulating the production of cyclic guanosine monophosphate (cGMP) in the target cell, leading to the relaxation of smooth muscle and vasodilation. Vitamin D, testosterone, cortisol, and antidiuretic hormone do not have a known effect on smooth muscle relaxation.