Database trigger across multiple postgres databases

I have a question regarding postgres Trigger.
We have two applications which connect to two different databases (Both are postgres).
Is it possible to create a trigger (row based) in one database say A, which can access another database say B and updates a table there.

In brief, Is it possible to create Trigger in one database, which can connect to another database for making an update in the other database table.

thanks,

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