급성실형시의 근력저하

Abstract

Adults rabbits were subjected to bleeding to lower their mean arterial blood pressure to 30-4j mmHg in 15 minutes. The blood pressure was maintained at a desired level by fixing the height of the reservoir connected to the artery. The performance of the gastrocnemius was studied at the hypotensive state by taking the curves of tetanic contraction before hemorrhage, at 30 minutes and at one hour of hypotensive period. The peak of the tetanus curve and the heights at 5 seconds and 10 seconds were measured. AU values were expressed as the ratio to the peak height of the curve which was attained before the bleeding. The animals were devided into 3 groups. They were the control group, hemorrhage group and the prednisolone treated group. In the hemorrhage group the gastrocnemius muscles and sciatic nerves of both sides were exposed and the strings attached to the ends of the Achilles tendons were connected to the transducers(myographs). Sciatic nerves were cut and stimulating electrodes were placed on the distal ends in order to get the tetanic contraction curves of the gastrocnemius muscles. Immediately aftee the surgical procedure blood was taken through the canula inserted into the carotid artery, resulting in a predetermined hypotensive state. One of the gastrocnemius muscles was stimulated during the hypotensive state every 3 seconds with 1-2 volts square wave of 2 milliseconds duration. The opposite side was kept silent between the consecutive tetanic contractions. The animals of the prednisolone treated group were given prednisolone. 25mgjkg. body weight intraperitoneally one hour prior to the hemorrhage. The control group was exempted from the hemor• rhage. other surgical procedure being the same. Concentrations of plasma sodium , potassium and lactate were measured during the course. These components and water content of the muscles were also measured The results obtained were as follows: 1. In the control group the surgical procedure without hemorrhage brought deteriorations in the performance of the muscle as well as in the chemical components. Observations were limited to one hour in the present studies. 2. In the silent muscles of the hemorrhaged animals the performance was weakened progressive Iy. In the active muscles which were stimulated every 3 seconds during the hypotensive state, the change in the performance and the alteration of the chemical components were slight as comparing with the resting muscles. Repeated contractions at a slow rate seemed to bring beneficial effects on the muscular function in these adverse conditions. 3. In the prednisolone treated group. the function of the resting muscle was well preserved in the hypotensive state. In the active muscle. however. no improvement was noticed by the prednisolone administration.