Beta-adrenoceptor blockade and cardiovascular response to the cold pressor test

Seven healthy subjects immersed a hand in random order in either warm water or in cold water at 5 degrees C for 2 min, after taking orally a single dose of 120 mg of propranolol or a placebo in a double blind fashion. The cold stress resulted in a significant increase in blood pressure and the rate pressure product without a change in heart rate. Beta-adrenoceptor blockade did not affect the pressor response the cold. The changes induced by the cold stress in the cardiovascular variables in the placebo and propranolol experiments were not statistically different. The highest rate pressure product during the cold pressor test was about 109 units. This was well below the pain threshold value of about 200 found during exercise in patients with ischaemic heart disease. In the recovery phase, the cardiovascular variables reverted to pre-immersion values within 1 min inspite of continued low hand skin temperature.