In spite of numerous work done in this field it is not clarified so far how the acceleration of the capillary blood flow, of glucose uptake, and of muscle growth occurring during work and after ischemia is controlled in muscle tissue. Since the signal for the induction of these responses stems from inside the cell, tissue factors have been postulated which should be responsible for the enlargement of the capillary net and the improvement of the tissue's insulin sensitivity. The accumulation of new evidences during the last few years points to an involvement of the kallikrein-kinin-prostaglandin system.