I am relatively new to Physiology, and I've just learnt about muscle tone. I however find it difficult to understand the electrical changes that initiate (and/or accompany) muscle tone in smooth muscles . To be specific, I know that action potentials(AP) cause muscle contraction (just like they cause nerve impulse propagation), and I also know that smooth muscle tone is a result of irregular contractions of the muscles at rest. How then can these muscles contract when no AP is generated at rest?
PS: This question has been edited to achieve more clarity.