| Abstract: | Local blood flow regulation of the foot was studied in 15 normal subjects and in nine migraine patients. Changes in arterial and venous pressures were induced by lowering and elevation of the limb. Changes in blood flow were estimated from the changes in the wash-out rate of a subcutaneous 133-Xenon depot. The local vasoconstrictor response to increased venous pressure elicited during lowering was identical in the normal subjects and in the migraine patients. During elevation, however, an abnormality in the autoregulation of blood flow could be demonstrated, as a decrease in blood flow during elevation to +40 cm was more pronounced in the patients than in the normal subjects (P = 0.04). About 3 h after 0.5 mg ergotamine tartrate/70 kg body weight i.v. the local regulation of blood flow had markedly changed in normal subjects as well as in migraine patients. During elevation to +20 and to +40 cm, blood flow increased significantly (P = 0.01 and P = 0.02). In two subjects the isotope depot was infiltrated with lidocaine and the ergotamine-induced increase in blood flow during elevation was blocked. The results may indicate that the veno-receptor of the veno-arteriolar reflex underlying the local vasoconstrictor response is a tension receptor, which due to the veno-constrictor effect of ergotamine is triggered even at heart level. |
