mechanisms of blood flow increase induced by electrical stimulation

previous studies have shown that electrical stimulation (es) increases blood flow, but the exact mechanisms are not clear. the present study was designed to clarify some of the underlying mechanisms involved in this phenomenon. white adult rabbits lt.-6 months old were used. animals were anesthetized by sodium pentobarbital (40 mg/kg, iv) and skin blood flow in the thoracic back was recorded using a laser doppler flowmeter (ldf). square waves (20 hz frequency, 0.5 ms duration, 15 v strength) were applied through a pair of surface electrodes placed on the skin of animals. drugs were applied to the skin close to the tip of the laser optic probe. the results obtained were as follows: 1. electrical stimulation increases local blood flow. 2. blood flow increases dose-dependently by administration of substance p (sp). 3. the response of es on local blood flow was augmented in the presence of sp. 4. sp-antagonists did not have any effect on basal local blood flow. 5. the effect of es was attenuated in the presence of sp-antagonists, but this was not statistically significant. 6. local blood flow increased in reserpinized animals. 7. the electrically-induced increase in blood flow in reserpinized animals was not statistically different from that of non-reserpinized animals. based on the above findings, it could be concluded that release of vasodilating compounds such as sp from sensory nerve endings may contribute in electrical stimulation and increase blood flow.