The primary objective of this prospective, observational study is to compare muscle sympathetic nerve activity at rest and during stress between female patients with Takotsubo syndrome and healthy, matched volunteers. * Do Takotsubo patients have an increased sympathetic nerve activity compared to controls? * Do Takotsubo patients have an exaggerated sympathetic nerve activity response to stress? * Does the sympathetic nerve activity response to stress in Takotsubo change after receiving the beta blocking agent metoprolol? Participants will be examined with muscle sympathetic nerve activity recording in the peroneal nerve at rest and during cold pressor test. After intravenous injection with beta blocking agent (metoprolol) or placebo (saline) in a 1:1 randomized fashion, muscle sympathetic nerve recording at rest and during stress will be repeated.
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Resting MSNA
Timeframe: During 5 minutes rest
MSNA increase during CPT
Timeframe: During the last 60 seconds of the CPT