Ischemia Increases the Twitch Latent Period in the Soleus and Extensor Carpi Radialis Longus Muscles from Adult Rats

Abstract

Complete ischemia and reperfusion effects on twitch force (∫(F·t)), twitch latent period (TLP), maximal rate of rise of twitch tension (δF/δt), and twitch maximum relaxation rate (TMRR) were assessed. We divided 36 adult rats into four groups; two control groups (n = 9), a group undergoing 1 hour of ischemia followed by 1 hour of reperfusion (n = 9), and one group exposed to 2 hours of ischemia followed by 1 hour of reperfusion (n = 9). We have induced twitch contractions every 10 minutes in the soleus and the extensor carpi radialis longus (ECRL). Twitch contractions were recorded and then analyzed for ∫(F·t), TLP, (δF/δt), and TMRR. During 1 hour and 40 minutes of ischemia, TLP increased to 179 ± 24% (p < 0.05) in the soleus and to 184 ± 16% (p < 0.05) in the ECRL, an effect that was partially recovered during 1 hour of reperfusion. This increase started after 20 minutes of ischemia in the soleus and after 40 minutes of ischemia in the ECRL. The increase was faster in the ECRL and peaked at the same time for both muscular groups. ∫(F·t) and (δF/δt) decreased during 1 hour of ischemia to 46 ± 7% (p < 0.05) in the soleus and to 40 ± 7% (p < 0.05) in the ECRL. TMRR decreased during 1 hour of ischemia to 39 ± 5% (p < 0.05) in the soleus and to 54 ± 8% (p < 0.05) in the ECRL. During 1 hour of reperfusion all of them recovered close to control values.

Rat skeletal muscle-nerve preparation to teach skeletal muscle physiology

“…The time of stimulation is indicated by a vertical line in the graph. The latent period is mainly due to the time taken for the impulse to travel through the nerve from the point of stimulation to the neuromuscular junction (6). The time interval between the onset of contraction and the peak of contraction is the contraction period.…”

Cold Pack Accelerate Recovery in Functional Parameters Post Ischemia Reperfusion Injury in Skeletal Muscle

“…The procedure for the generation of ischemia-reperfusion injury to the Soleus muscle has been previously described [13,[23][24][25][26]. Once anesthetized, rats were placed in prone decubitus position with the right inferior extremity in a pneumatic tourniquet above the knee joint.…”

“…Preparation procedures for in-vivo functional measurements of Soleus muscle were previously described [12,13,26,27]; rats were placed in prone position, the distal tendon was isolated, cut and tied with surgical thread and was assured to the force transducer (Powerlab MLT1030/A). Muscle temperature remained around 34+/-0.5°C through a cooling chamber connected to a bath of water circulation and measured by a digital thermometer.…”

“…Histological studies of ischemia-reperfusion injury in skeletal muscle have shown edema, microvascular dysfunction, inflammation, a decrease in muscle fiber diameter and loss of angular contours, all of which are associated with morbidity and the dysfunction of skeletal muscle [7][8][9][10][11]. Moreover, studies of muscle function under isometric conditions show that maximum tetanic force and contraction rate in oxidative and glycolytic muscle drops during ischemia, and vastly recover throughout the first hour of reperfusion [12][13][14]. However, as the ischemic period extends, all functional parameters decline in both oxidative and glycolytic muscle groups; in fact, after two hours of ischemia, those functional parameters decrease to 80 and 90% of the values found before ischemia [12,13].…”

“…Moreover, studies of muscle function under isometric conditions show that maximum tetanic force and contraction rate in oxidative and glycolytic muscle drops during ischemia, and vastly recover throughout the first hour of reperfusion [12][13][14]. However, as the ischemic period extends, all functional parameters decline in both oxidative and glycolytic muscle groups; in fact, after two hours of ischemia, those functional parameters decrease to 80 and 90% of the values found before ischemia [12,13]. Cryotherapy is one of the main therapies used in the acute stages, along with compression and elevation, since its effect on arterial and venous vasoconstriction leads to a decreased blood flow to the treated area, thus reducing both edema and inflammation induced by trauma [15][16][17][18][19].…”