The turmoil in global stock markets and the plunge in oil prices are shaking Russia’s economy, already wobbly from being cut off from Western finance by sanctions.

Russia’s currency, the ruble, fell briefly on Thursday to 85 to the dollar, a record low, before creeping back to 82.5 by the close of trading.

With alarm rising among policy makers, the chairwoman of Russia’s central bank, Elvira Nabiullina, canceled a trip to the World Economic Forum in Davos, Switzerland, where she was scheduled to appear on Friday.

The central bank announced the cancellation without elaborating. Interfax, a nongovernment news agency, reported that the central bank held an emergency meeting Thursday evening with Russian bankers.