title: Coffee acutely increases sympathetic nerve activity and blood pressure independently of caffeine content: role of habitual versus nonhabitual drinking.
abstract: BACKGROUND
  Coffee is the most abundantly consumed stimulant worldwide. However, its cardiovascular safety remains controversial. Possible health hazards have been related to its main ingredient, caffeine. Activation of the sympathetic nervous system by coffee may enhance cardiovascular risk; however, it is unclear whether this effect of coffee is related to caffeine or other substance(s) also contained in decaffeinated coffee.
  
  
  RESULTS
  In 15 healthy volunteers (6 habitual and 9 nonhabitual coffee drinkers) arterial blood pressure (BP), heart rate, and muscle sympathetic nervous activity (MSA) were continuously recorded before and after drinking a triple espresso or a decaffeinated triple espresso or after intravenous administration of caffeine (250 mg) or placebo (saline) in the same subjects. There was a significant time x condition interaction for the intravenous caffeine and placebo conditions for MSA, with caffeine showing a significant increase in MSA at 60 minutes (53.2+/-14.1% total activity) and the placebo group showing no effect. A similar significant time effect was found for coffee drinking (54.1+/-22.5% total activity). Habitual and nonhabitual coffee drinkers demonstrated similar changes in MSA and BP after intravenous caffeine, whereas coffee drinking increased BP in nonhabitual drinkers only, despite comparable increases of MSA and plasma caffeine levels. Nonhabitual coffee drinkers showed similar activation of MSA and BP after caffeine infusion, coffee, or decaffeinated coffee.
  
  
  CONCLUSIONS
  Acutely, coffee and caffeine induced comparable increases in MSA and BP in nonhabitual coffee drinkers, whereas habitual coffee drinkers exhibited lack of BP increase despite MSA activation to coffee. Because decaffeinated coffee also increases BP and MSA in nonhabitual drinkers, ingredients other than caffeine must be responsible for cardiovascular activation.
authors.affiliation: CardioVascular Center, Cardiology, University Hospital Zürich, Switzerland. roberto.corti@DIM.USZ.ch
authors.forename: Roberto
authors.initials: R
authors.lastname: Corti
authors.forename: Christian
authors.initials: C
authors.lastname: Binggeli
authors.forename: Isabella
authors.initials: I
authors.lastname: Sudano
authors.forename: Lukas
authors.initials: L
authors.lastname: Spieker
authors.forename: Edgar
authors.initials: E
authors.lastname: Hänseler
authors.forename: Frank
authors.initials: F
authors.lastname: Ruschitzka
authors.forename: William F
authors.initials: WF
authors.lastname: Chaplin
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Lüscher
authors.forename: Georg
authors.initials: G
authors.lastname: Noll
mesh_terms: D000284:Administration, Oral; D000328:Adult; D001794:Blood Pressure / Q000187:drug effects* / Q000502:physiology; D002110:Caffeine / Q000008:administration & dosage / Q000494:pharmacology*; D003069:Coffee / Q000737:chemistry; D004562:Electrocardiography / Q000187:drug effects; D005247:Feeding Behavior; D006439:Hemodynamics / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D007275:Injections, Intravenous; D009132:Muscles / Q000294:innervation; D010543:Peroneal Nerve / Q000187:drug effects / Q000502:physiology; D012016:Reference Values; D013564:Sympathetic Nervous System / Q000187:drug effects* / Q000502:physiology; D013997:Time Factors
chemical_list: D003069:Coffee; D002110:Caffeine