RESUMO
The effects of electrical acupuncture at the patellar tendon and electrical stimulation of the femoral nerve on patellar tendon blood flow were evaluated using laser Doppler flowmetry in anesthetized rats. In most subjects the blood flow in the patellar tendon rapidly decreased for 30 seconds after the start of local electrical acupuncture and then increased above baseline. Changes in blood flow did not necessarily follow changes in arterial blood pressure. Changes in tendon blood flow induced by electrical stimulation of the femoral nerve were similar to those induced by electrical acupuncture at the patellar tendon. Arterial blood pressure and heart rate were not affected by electrical stimulation of the femoral nerve. Phentolamine administration abolished the decreased patellar tendon blood flow seen after initiating electrical acupuncture at the patellar tendon, whereas atropine abolished the increased patellar tendon blood flow seen after terminating electrical acupuncture at the patellar tendon. Furthermore, atropine did not evoke increased blood flow following electrical stimulation of the femoral nerve. These results suggest that the decrease of blood flow seen after initiating electrical acupuncture may be controlled by sympathetic vasoconstrictor nerves and the increase of blood flow following electrical acupuncture may be controlled by cholinergic vasodilator nerves.
RESUMO
Evidence of an increased resting blood flow in the tendon against the adjacent muscle was confirmed in the <I>in situ</I> hindlimb preparation of a rabbit anesthetized with urethane. The tendon tissue blood flow was found to be modulated by nervous and mechanical factors. The effect of nervous control was demonstrated by the denervation of the sciatic nerve, which showed a gradual increase in the resting blood flow in the tendon and muscle after being severed. During local muscle exercise, the increase of tendon tissue blood flow observed was minimal in comparison with the adjacent muscle. The tendon surrounding tissue blood flow showed site-dependent characteristics along the longitudinal tendon bundles. Evidence of tendon vascular structure in the rabbit species was confirmed by observing capillaries in cross sectional fascicles and longitudinal and transversal vessels in the paratenon of the Achilles tendon. These results strongly suggest a physiological model of local tissue temperature regulation and fluid dynamics in the biological system.