The reactivity of isolated venous preparations to electrical stimulation

Summary The reactivity of spiral strips and isolated segments of the lateral saphenal vein of the dog was investigated. In a first series of experiments the influence of progressively increasing distension on the isotonic or isometric reactions of both preparations to a constant electrical stimulation was examined. It appeared that in every case the reaction first increases with progressive distension. Whenever the venous wall becomes overstretched, the amplitude of the reaction diminishes gradually. In a second series of experiments, spiral strips and isolated segments were prepared from the same veins and their sensitivity to increasing stimulation frequencies tested at the optimal point of their distension-reaction relation, both in isotonic and isometric conditions. From these experiments it appeared that the isotonic preparations are more sensitive than the isometric, and that the sensitivity of the isolated segment is also greater than that of the spiral strip.