Exercise hyperemia on hindlimb muscles in anesthetized spontaneously hypertensive rats / 体力科学

Muscle blood flows by means of hydrogen gas clearance method were measured on hindlimb muscles in sedentary control (nE) and exercised (Ex) spontaneously hypertensive rats (SHR) . SHR and Wistar control rats (WCR) were divided into two groups at 7 weeks of age ; SHRnE, SHREx and WCRnE, WCREx. Exercised rats were bred in cages with rotating wheels capable of running voluntarily for additional 10 weeks. Body weights of exercised groups in both SHR and WCR were lower than those of sedentary controls, whereas food consumptions of exercised rats tended to be more than those of sedentary controls. Ratios of the heart weight to the body weight of SHR and WCR were higher in exercised groups. There was no significant difference in systolic blood pressure obtained by an indirect tail-cuff method between exercised and sedentary control SHR. Resting blood flows in both M. Gastrocnemius and M. Soleus showed lower values in SHR groups than those in WCR groups. Postexercise blood flows at 1 Hz and 5 Hz were higher in exercised groups. These results suggest that peripheral adaptability of blood flow control to the exercise is still normal on hindlimb muscles in SHR.

A histochemical study on the differentiations of anterior horn cell of the spinal cord and hindlimb muscle fibre in the rat / 体力科学

Wistar strain male albino rats were sacrificed at 1, 3, 5, 7, 9, 11, 13, 15, 17, 19 and 21 days of age, and the histochemical properties of nerve cell and muscle fibre were examined.<BR>We obtained the following differentiation process in the muscle with postnatal growth;<BR>phase I (newborn-7 days) undifferentiated fibre<BR>phase II (7-15 days) FT fibre ST fibre<BR>phase III (after 15 days) FG fibre FOG fibre SO fibre<BR>On the other hand, histochemical differentiation of nerve cell was recognized earlier than that of muscle fibre, and there was no redistribution of soma type with growth.<BR>Therefore, it may be said bhat histochemical differentiation process in the muscle is largely effected by the neuronal influences exerted from the lower motoneurons.

Effect of hip and knee joint angles in response to a step out movement / 体力科学

The purpose of the present study was to determine whetehr differences exist between nine experimental conditions mixing 10°, 40°and 70°of hip joint angles with knee joint angles, when thirteen subjects performed the same response task. In the experiment 1, each subject was asked to stand on the inside two of the four mat switches (500×700 mm) and keep the assigned joint angles during a second of preparatory period. After the period, each subject was asked to respond with a step out on either the right or the left outside mat switch as quickly as possible. Then the data was collected analyzing the whole body choice response time (RESPONSE TIME) defined as the interval time from the signal to respond with step out, the whole body choice reaction time (REACTION TIME) defined as the interval time from the signal to reaction with lifting the leg for responding to the step out, and the movement time (MOVEMENT TIME) defined as the interval time subtracting RESPONSE TIME from REACTION TIME. Moreover, in the experiment 2, the data was collected and analyzed from the onset time of various forces from the two force platforms on which each subject stood instead of the mat switch and EMG which was led from the right side of m. rectus femoris, m, biceps femoris, m. gastrocnemius, m. tibialis anterior and the left side of m. quardriceps femoris, during performance of the response task. The results were as follows:<BR>1. The subjects' posture with each 70°flexion of the hip and the knee joint revealed the shortest RESPONSE TIME, because of the shortened MOVEMNT TIME, compared with the other posture. Conversely, the posture with 70° flexion of the knee joint showed an expanded REACTION TIME.<BR>2. The knee joint angle was an important factor effecting both REACTION TIME and MOVEMENT TIME, rather than the hip joint angle for the task of the experiment, since flexion of the knee joint expanded the REACTION TIME, but shortened the MOVEMENT TIME.<BR>3. The result of the force platform measurements indicated that the posture with each 70°flexion of the hip and the knee joint was shorter than that with each 10°flexion of them at the onset time of the first reaction force after the reaction signal, and that the order of response for the task was beginning at the leg for responding, followed by the other leg for keeping stability.<BR>4. Conclusive evidence for a shortened RESPONSE TIME was found in the facilitation of the central nervous system, which revealed the preliminary muscle activity and the stabilizing of the posture.

RELATIONSHIP BETWEEN ALPHA-BLOCKING AND SLOW POTENTIAL CHANGES PRECEDING REACTION MOVEMENT / 体力科学

In order to investigate the association of alpha-blocking with motor set under the condition of simple reaction movement, the scalp distribution of alpha wave envelope recorded by averaging method was compared with that of slow potential changes. The results were as follows.<BR>1) The slow potential changes (readiness potential, early and late component of CNV) were large over the central and frontal area. The readiness potential was larger over the contralateral than the ipsilateral central motor area, while the early component of CNV showed bilateral spread. The late component of CNV showed the similar scalp distribution to that of readiness potential, but the latter was much more lateralized.<BR>2) The alpha-blocking was bilaterally symmetrical over the central and occipital area under the condition of photic stimulus without movement. But the alpha-blocking accompanying preparatory signal increased over the frontal and central area compared with control alpha-blocking, and was larger over the contralateral than ipsilateral central motor area.<BR>3) The maximal alpha-blocking rate showed to correlate negatively with its latency under each condition. The difference in alpha-blocking rate at the onset of the imperative stimulus between reaction movement and control showed to correlate negatively with reaction time.<BR>From these findings, it seems that alpha-blocking accompanying preparatory signal reflects not only input system but also readiness potential component, and that in temporal respect alpha-blocking increases at the onset of movement.

MOVEMENT-ASSOCIATED CORTICAL POTENTIAL PRECEDING VOLUNTARY MOVEMENT / 体力科学

The purpose of the present experiment is to identify, in detail, results of the preceding experiment of authors that the amplitude of N<SUB>1</SUB> potential was dominant over motor cortex area contralateral to moving limb, with bipolar lead and is to investigate negative potential appearing the scalp preceding voluntary movement depends on a precaution stimulus or on readiness of movement execution only.<BR>In addition to, discussing' the difference of CNV (Contingent Negative Variation) and N<SUB>1</SUB> potential is, also, the purpose of the present experiment.<BR>The present experiment gave the following results.<BR>1. The results obtained with monopolar lead were that the amplitude of N<SUB>1</SUB> potential was maximal at lead placement Cz in all movement.<BR>2. The results obtained with bipolar lead were that the amplitude of N<SUB>1</SUB> potential showed, relatively, lower tendency in the combination within central area and showed, relatively, higher tendency in the combination of other lead placement to central area.<BR>3. Judging from all the scalp, the amplitude of N<SUB>1</SUB> potential showed high tendency at central area.<BR>4. In particular, clear difference was identified between the latency of CNV and that of N<SUB>1</SUB> potential.<BR>5. As showing much the same amplitude except for lead placement Cz, CNV extended from central area over the scalp.