Question

how does high dose of muscarinic agonists cause hypertension since there is no parasympathetic nerve innervates vascular smooth muscle?

Answer 1

Although not my area of expertise, I found your question interesting. It seems this can occur because, although there's no parasympathetic innvervation, vascular smooth muscle does contain muscarinic receptors (M1 & M3). To quote Harvey "This reflects the fact that muscarinic receptors are expressed throughout the cardiovascular system, even though they are not always involved in mediating parasympathetic responses." Handb Exp Pharmacol. 2012;(208):299-316.