Blood Flow in the Human Calf during Tobacco Smoking.

THE cutaneous vasoconstrictive effect of tobacco smoking has been demonstrated by several groups.1-4 In about 50 per celit of people, smoking has been reported to diminish the increase in foot blood flow, called reactive hyperemia, which follows a period of arterial occlusion. Experiments on patients with sympathectomized limbs showed that the decrease in reactive hyperemia was mediated through the sympathetic nervous system.5 Few studies are available concerning the effeet of tobacco smoking on skeletal muscle blood flow. Abramson et al.6 found no change or very small increases in plethysmographic forearm blood flows during cigarette smoking. Formerly, it was considered that the plethysmographic blood flow measurements in the calf or forearm were actually representative of muscle flow because the ratio of skin to muscle in these areas was small. However, Cooper and his co-workers7 have shown, by using the technic of adrenalin iontophoresis to stop cutaneous blood flow, that the skin may under certain conditions account for as much as 60 per cent of the resting forearm blood flow. Employing a plethysmograph, it is apparent that increases in muscle blood flow may be hidden or exaggerated by changes in skin flow. Therefore, the effect of tobacco smoking was investigated using the disappearance rate of a radioisotope from skeletal muscle as a measure of its capillary blood flow.