Force-Velocity Relationship of Shortening of Blood Vessel of the Common Frog Rana temporaria during Phasic and Tonic Contractions

摘要

The relationship between shortening velocity and the applied external load(force-velocity)was studied for vena cava posterior of the frog Rana temporaria.This relationship was determined in 15 s,2 and 20 min after the beginning of isometric contraction induced by a high KC1 concentration(110 mmole/1).It was found that maximal shortening velocity(V_0)was the highest at the 15th s after the beginning of the isometric contraction and amounted to 0.125(+-)0.009 L_0/S(n=4);then it decreased progressively to 0.058(+-)0.005 L_0/S at the 20th min,respectively.On the contrary,the isometric tension value increased and reached its peak in 5 min after the beginning of contraction,then it decreased slightly.Such phenomenon indicates the occurrence of attached non-cycling bridges.The A/p_0 parameter was equal to 0.15(+-)0.03 and 0.33(+-)0.06 at the 15th s and the 20th min,respectively.