DIVERGENT CHANGES OF FLOW-THROUGH INDIVIDUAL BLOOD-VESSELS UPON LOCALIZED HEATING

The changes of microregional perfusion in a hamster cheek pouch membra ne were investigated. The vessel network of the membrane was visualize d by preparing a transparent chamber, which was heated with circulatin g water at 42 degrees C. Blood perfusion was monitored by using a lase r Doppler flowmeter (LDF), which was used either in a conventional way by positioning the probe stationary or in a novel way by constantly m oving the probe over the surface of the chamber (scanning). When a seg ment of tissue was subjected to the LDF scanning, the profile of scann ed LDF values was well correlated with the distribution of vessels. Th erefore, this scanning technique was useful in localizing the probe in tissues with respect to vessels. Since the scanning can be repeated e very other minute, this technique also offered continuous monitoring o f tissue blood flow at multiple sites. Upon heating, different vessels individually responded to the first and second beatings followed by c oolings, suggesting a heterogeneous heat response in the connective ti ssue of the hamster cheek pouch membrane. This scanning technique prov ed very useful in collecting information for the study of the heteroge neous nature of blood how in normal and tumour tissues.