A muscarinic receptor antagonist is administered resulting i

A muscarinic receptor antagonist is administered resulting in...

A: elimination of vasomotor tone with a subsequent decrease in systemic arterial blood pressure

B: elimination of vagal tone on the heart leading to a decrease in heart rate

C; paralysis of respiratory muscles

D: elimination of vagal tone on the heart leading to an increase in heart rate

Solution

Muscarinic receptors are present on the surface of cells (vital organs including brain, heart, lungs) and are associated with differential effects on different organs. It is used as anti-Parkinson\'s disease, in management of asthama, dilation of pupil, increase in heart rate etc.

A muscarinic receptor antagonist causes hyperpolarization of the sinu-arterial node due to blockage of vagal nerve. The acetylcholine is neurotransmitter which relays information from one cell to another. Their receptors are present on the cells and can respond to cholinergic or muscarinic ligands based upon their location and function.

Thus, choice D is the appropriate answer.