What may be used to antagonize respiratory depression caused by xylazine?

Yohimbine is an effective antagonist for respiratory depression caused by xylazine because it specifically counteracts the effects of alpha-2 adrenergic agonists like xylazine. Xylazine is known to induce sedation and respiratory depression by acting on these adrenergic receptors, primarily decreasing the central nervous system stimulation of respiratory drive. Yohimbine competes for the same receptor sites and reverses the sedative and anesthetic effects of xylazine, leading to the restoration of normal respiratory function.

In contrast, other options do not have the targeted mechanism required to reverse xylazine's effects. Atropine is primarily used to increase heart rate and does not specifically address respiratory depression. Propranolol works as a non-selective beta-blocker, also not directly influencing alpha-2 receptors or respiratory drive. Naloxone is primarily an opioid antagonist and would not apply to xylazine administration since it acts on a different receptor pathway altogether. Thus, yohimbine is the most appropriate choice for antagonizing respiratory depression associated with xylazine use.