Which of the following effects do cholinergic antagonists typically produce?

Cholinergic antagonists, also known as anticholinergics, primarily block the action of acetylcholine at muscarinic receptors. This inhibition leads to several physiological responses that are opposite to what cholinergic agonists would cause.

One of the hallmark effects of cholinergic antagonists is bronchodilation. By blocking the muscarinic receptors present in the bronchial smooth muscles, these agents prevent bronchoconstriction and promote the dilation of the airways. This action is particularly beneficial in conditions such as asthma and chronic obstructive pulmonary disease (COPD), where the widening of air passages can provide relief from obstructive symptoms.

In contrast, the other responses mentioned, such as decreased heart rate, increased secretions, and bronchoconstriction, reflect actions typically associated with cholinergic agonists rather than antagonists. Thus, the role of cholinergic antagonists in inducing bronchodilation is a significant pharmacological effect that helps in managing respiratory conditions.