Influence of slow calcium-channel blockade on the cardiovascular effects of coffee

An increase in blood pressure after coffee and caffeine has recently been reported. A possible pharmacological mechanism for this pressor response is a rise in the intracellular calcium concentration, caused by an increase in calcium influx due to a direct effect of caffeine. Accordingly, the cardiovascular effects of drinking coffee after placebo and verapamil 3 X 80 mg in 1 day in 10 normotensive volunteers have been examined in a single-blind study. After placebo, coffee led to an increase in blood pressure (7/14 mm Hg), and a fall in heart rate (-7 beats/min); forearm blood flow did not change. Plasma epinephrine rose (257%), plasma norepinephrine did not change and the plasma renin activity fell significantly. The haemodynamic and humoral changes after coffee were not altered by pretreatment with verapamil. It is concluded that increased transmembrane calcium influx after caffeine does not appear to be an important pharmacological mechanism for the circulatory effects of coffee.