Fig. 2.

Caffeine-ethanol mixture fails to constrict cerebral arteries in vitro. (A) Diameter trace from a pressurized middle cerebral artery from rat. After development of myogenic tone, the artery was probed with 60 mM KCl to test maximal contraction. After KCl washout, the artery chamber was perfused with either (A) 50 mM ethanol or (B) 50 mM ethanol+10 µM caffeine mixture. (C) Average change in artery diameter evoked by KCl, 50 mM ethanol, or 50 mM ethanol + 10 µM caffeine mixture. Last set of bars also depicts averaged percentage of myogenic tone. Hollow bars (group 1) represent data from arteries that were exposed to ethanol only (n = 4); black bars (group 2) reflect data from arteries that were challenged with the ethanol + caffeine mixture (n = 6). *Different from constriction by 50 mM ethanol (P < 0.05).