Abstract
The distal one-third of a rabbit earlobe was immersed into liquid of 0°C or 42°C with the animal in a supine position. Laser-Doppler flowmeter pickups were placed on the skin surface over tissue area avoiding large branches of central artery. Upon immersion into cold water, the initial fall seen in recordings taken by the thermistor method was not necessarily observed by the laser method. Sometimes even a rise of flow rate was noticed. Later, decreases in the rate were observed. Cold-induced blood flow oscillation was observed with the laser method even when vasooscillation could not be detected by the thermistor. After removal from cold water, the earlobe was immersed in hot water. A few minutes later, a characteristic flow oscillation with period of approximately 8 to 27 sec appeared in all nine rabbits. The heat-induced oscillation indicated amplitudes (wave heights) higher than those in controls and cold exposure experiments. The wave pattern was featured by the increased ratio of wave height/period, which means an increased kurtosis of the waves. This kind of activation was very common in the hot liquid exposure. The wave pattern for some cases seemed very regular with a smaller coefficient of variation (CV) of the period, compared with that in the control. The CV was usually less in period than in amplitude.
