BLOOD-FLOW RATE IN ARTERIOVENOUS ANASTOMOSES AND CAPILLARIES IN THUMB, FIRST TOE, EAR LOBE, AND NOSE

Measurements of blood flow rate in the pulp of the thumb, the first to e, the ear lobe. and the nose were performed using the heat-washout me thod, and the Xe-133-washout method under orthostatic changes in human s. Blood flow rate measured by the heat-washout method in the thumb wa s about 127.5 ml (100 g . min)(-1) at heart level in two subjects, (n= 10), and in the pulp of the first toe in 6 subjects (n=12) 49.3 ml (10 0 g . min)(-1) at heart level. Above heart level blood flow rate decre ased with the falling pressure head, and 50 cm below heart level blood flow remained unchanged compared to heart level. The arterioles suppl ying the capillaries in this region showed autoregulation of blood flo w to 50 cm above heart level, but a veno-arteriolar reflex was not pre sent. Blood now rate in the ear lobe and on the side of the nose showe d a similar pattern of reaction, with a blood now rate in the arteriov enous anastomoses of about 100 ml (100 g . min)(-1) in sitting positio n.