Observations of cochlear blood flow dynamics using the laser Doppler flowmeter.

The cochlear blood flow of normal adult guinea pigs was measured by a laser Doppler flowmeter. The validity of this flowmeter was ascertained by its specificity for blood flow and its sensitivity to blood flow changes. Angiotensin II was infused into the animals and asphyxia was induced. The responses of the cochlear blood flow showed a close correlation with those of the systolic blood pressure. These results suggest a passive aspect in the physiology of cochlear blood circulation. On the other hand, there was a negative correlation between the responses of auricular skin blood flow and those of systolic blood pressure to a certain dose range of angiotensin II. To clarify the specific details of inner ear blood flow, further studies of the hemodynamics of the inner ear blood circulation should be continued under various experimental conditions.