References

pendent of the carotid baroreflex. Phenylephrine and nitroglycerin affect venous compliance and venous re-turn to the heart, in addition to their effects on the peripheral arterial tree. Neck suction or pressure may change venous return from the head or may influence aortic baroreceptors in a direction opposed to the pre-sumed effect on carotid baroreceptors. When the ob-tained results from different studies using different measurement techniques are discrepant, and when, as in our study, the obtained results in the same subjects vary with the measurement technique, these operation-al definitions of baroreflex sensitivity become mean-ingless. We therefore caution clinical investigators against drawing inferences about overall baroreflex function on the basis of a single measurement technique. Acknowledgment The authors gratefully acknowledge the assistance of Joan Folio, R.N., and Bert Chidakel in conducting this study