‘Distensibility’ of the papaverine-relaxed vascular bed in human subcutaneous tissue

The effect of an increase in vascular transmural pressure upon the blood flow in two subcutaneous vascular beds, maximally dilated by papaverine was studied in 6 healthy humans. Blood flow was measured on the dorsum of the hand and at the lateral malleolus by the local ¹³³Xe washout technique. Increase in vascular transmural pressure was induced by lowering the labelled area various distances below heart level. Lowering the area caused an increase in blood flow. The increase was less pronounced in the legs than in the hand. As arterial perfusion pressure head remained constant during lowering, this indicates that the relative decrease in vascular resistance was smaller in the leg than in the hand. Experimental edema did not influence the relative decrease in vascular resistance. The results suggest that ‘distensibility’ of the resistance vessels is smaller in the leg than in the hand. This might be due to a structural adaptation of the vascular wall in vessels often subjected to increased hydrostatic pressure.     

Effect of endurance and sprint exercise on the sensitivity of glucose metabolism to insulin in the epitrochlearis muscle of sedentary and trained rats

Summary The effects of two types of acute exercise (1 h treadmill running at 20 m· min^–1, or 6 × 10-s periods at 43 m · min^–1, 0° inclination), as well as two training regimes (endurance and sprint) on the sensitivity of epitrochlearis muscle [fast twitch (FT) fibres] to insulin were measured in vitro in rats. The hormone concentration in the incubation medium producing the half maximal stimulation of lactate (la) production and glycogen synthesis was determined and used as an index of the muscle insulin sensitivity. A single period of moderate endurance as well as the sprint-type exercise increased the sensitivity of la production to insulin although the rate of la production enhanced markedly only after sprint exercise at 10 and 100 U· ml^–1 of insulin. These effects persisted for up to 2 h after the termination of exercise. Both types of exercise significantly decreased the muscle glycogen content, causing a moderate enhancement in the insulin-stimulated rates of glycogen synthesis in vitro for up to 2 h after exercise. However, a significant increase in the sensitivity of this process to insulin was found only in the muscle removed 0.25 h after the sprint effort. Training of the sprint and endurance types increased insulin-stimulated rates of glycolysis 24 h after the last period of exercise. The sensitivity of this process to insulin was also increased at this instant. Both types of training increased the basal and maximal rates of glycogen snythesis, as well as the sensitivity of this process to insulin at the 24^th following the last training session. It was concluded that in the epitrochlearis muscle, containing mainly FT fibres, both moderate and intensive exercise (acute and repeated) were effective in increasing sensitivity of glucose utilization to insulin. Thus, the response in this muscle type to increased physical activity differs from that reported previously in the soleus muscle, representing the slow-twitch, oxidative fibres in which sprint exercise did not produce any changes in the muscle insulin sensitivity.     

综合ICU中低年资护士培训方法探讨

目的探讨为综合ICU培养合格的护理人员的方法。方法根据ICU护士应具备的素质及低年资护士的特点,采用定期集中培训、一对一带教、参加护理查房等方法,对基础理论和基本技能进行强化,重点加强了ICU专科护理知识地训练。结果通过客观考核和主观考核,效果良好。结论经过为期12个月两个时段较规范的岗位培训,低年资护士能较好的适应ICU工作。     

Physical training and fasting erythrocyte activities of free radical scavenging enzyme systems in sedentary men

Summary Effects of 10 weeks of physical training on free radical scavenging enzyme systems in erythrocytes were investigated in 7 sedentary healthy male students. The training consisted of running over 5 km, 6 times/week. Their maximum oxygen uptake and 12 min walk-run performance increased significantly after training. Of the antioxidant enzyme systems examined in the erythrocytes, both catalase activity and concentration and total glutathione reductase (GR) activity also showed significant increases following the training. The erythrocyte GR activity coefficient also increased significantly. These results suggest that chronic aerobic exercise increases riboflavin requirements and has some positive effects on antioxidative processes.     

Bovine colostrum supplementation does not affect plasma buffer capacity or haemoglobin content in elite female rowers

It has been reported that bovine colostrum (BC) supplementation improves buffer capacity () during exercise, but whether the improvement results from changes in tissue and/or blood buffer systems has not been determined. The purpose of the present study was to examine the effect of supplementation with BC on blood buffer systems. Thirteen elite females rowers were supplemented with 60 g·day^–1 of either BC (n=6) or whey protein (WP, n=7) during 9 weeks of pre-competition training in a randomised, double-blind, placebo-controlled, parallel design. All subjects undertook the study as a group and completed the same training program. Resting haemoglobin (Hb) concentration and plasma buffer capacity (p) (determined by titration with HCl) were measured pre- and post-supplementation. There were no differences in macronutrient intakes (P>0.56) or training volumes (P>0.99) between BC and WP during the study period. There were no differences in Hb [BC 13.28 (0.28) mg·dl^–1, WP 13.70 (0.26) mg·dl^–1; P=0.45] or p [BC 14.8 (1.1) nmol HCl·ml^–1·pH^–1, WP 14.8 (0.5) nmol HCl·ml^–1·pH^–1; P=0.68] between groups at week 0. p increased in both groups during the study period (P<0.001), but the increases were not significantly different between groups (P=0.52). Hb did not change significantly in either group (P=0.35). These data indicate that supplementation with BC does not affect p or Hb. We therefore suggest that adaptations in tissue buffer systems are responsible for the previously reported increases in buffer capacity that result from BC supplementation.     

Effect of endurance training on muscle fiber type composition and capillary supply in rat diaphragm

Summary Muscle fiber type composition and capillary supply in rat diaphragm were investigated after 14 weeks of endurance training: body weight and muscle fiber area were significantly decreased, the muscle fiber type composition, capillary to fiber ratio and number of capillaries around each fiber type were unchanged, and the capillary density and number of capillaries around each fiber relative to fiber type areas were significantly increased. These small fiber areas and increased capillary supplies in the trained rats would facilitate oxygen transport to all parts of the muscle fiber during exercise. It is concluded that the changes observed in the trained rat diaphragm appear to enhance the capacity for oxidative metabolism.     

The Na+, K+ pump in skeletal muscle: quantification,regulation and functional significance

In skeletal muscle, the Na⁺, K⁺ pump is predominantly situated in the sarcolemma (1000–3500 pumps per μm²). The total concentration can be determined in fresh or frozen biopsies (1–5 mg) using a ³H-ouabain binding assay. The values obtained have been confirmed by measurements of maximum ouabain suppressible Na⁺, K⁺-transport capacity in intact muscles as well as Na⁺, K⁺-ATPase-related enzyme activity in muscle homogenates. In the mature organism, the concentration of Na⁺, K⁺ pumps varies with muscle type and species in the range 150–600 pmol (g wet wt)^-1. In rat and human muscle, the concentration increases markedly with thyroid status. Semi-starvation and untreated diabetes reduce the concentration by 20–48%. K⁺ deficiency leads to a downregulation of up to 75%. Both in animals and in humans, training increases the concentration of Na⁺, K⁺ pumps in muscle, and inactivity leads to a downregulation. High-frequency stimulation elicits up to a 20-fold increase in the net efflux of Na⁺ within 10 s This is the major activation mechanism for the Na⁺, K⁺ pump, utilizing its entire capacity and possibly represents a drive on de novo synthesis of Na⁺, K⁺ pumps. A variety of hormones (insulin, insulin-like growth factor I, adrenaline, noradrenaline, calcitonin gene-related peptide, calcitonin, amylin) increase the rate of active Na⁺, K⁺ transport by 60–120% within a few minutes. This leads to a decrease in intracellular Na⁺ and hyperpolarization. In isolated muscles, where contractility is inhibited by high extracellular K⁺, such agents produce rapid force recovery, which is entirely suppressed by ouabain and closely correlated to the stimulation of K⁺ uptake and the decline in intracellular Na⁺. The observations support the conclusion that the Na⁺, K⁺ pump plays a central role in the acute recovery and maintenance of excitability during contractile activity.     

Changes in performance,maximal oxygen uptake and maximal accumulated oxygen deficit after 5, 10 and 15 days of live high:train low altitude exposure

Nineteen well-trained cyclists (14 males and 5 females, mean initial V˙O_2max 62.3 ml kg^–1 min^–1) completed a multistage cycle ergometer test to determine maximal mean power output in 4 min (MMPO_4min), maximal oxygen uptake (V˙O_2max) and maximal accumulated oxygen deficit (MAOD). The athletes were divided into three groups, each of which completed 5, 10 or 15 days of both a control condition (C) and live high:train low altitude exposure (LHTL). The C groups lived and trained at the ambient altitude of 610 m. The LHTL groups spent 8–10 h night^–1 in normobaric hypoxia at a simulated altitude of 2,650 m, and trained at the ambient altitude of 610 m. The changes to MMPO_4min, V˙O_2max and MAOD in response to LHTL altitude exposure were not significantly different for the 5-, 10- and 15-day treatment periods. For the pooled data from all three treatment periods, there were significant increases in MMPO_4min [mean (SD) 5.15 (0.83) W kg^–1 vs 5.34 (0.78) W kg^–1] and MAOD [50.1 (14.2) ml kg^–1 vs 54.9 (13.1) ml kg^–1] in the LHTL athletes between pre- and post-altitude exposure. There were no significant changes in MMPO_4min [5.09 (0.76) W kg^–1 vs 5.16 (0.86) W kg^–1] or MAOD [50.5 (14.1) ml kg^–1 vs 49.1 (13.0) ml kg^–1] in the C athletes over the corresponding period. There were significant increases in V˙O_2max in the athletes during both the LHTL [63.2 (9.0) ml kg^–1 min^–1 vs 64.1 (9.0) ml kg^–1 min^–1] and C [62.0 (8.6) ml kg^–1 min^–1 vs 63.4 (9.2) ml kg^–1 min^–1] conditions. In these athletes, there was no difference in the impact of 5, 10 or 15 days of LHTL on the increases observed in MMPO_4min, V˙O_2max or MAOD; and LHTL increased MMPO_4min and MAOD more than training at low altitude alone. Electronic Publication     

The Effects of Discrimination Training on Voluntary Control of Cephalic Vasomotor Activity

The present study was conducted to test Brener's calibration theory of visceral learning. It was hypothesized that training in discrimination of cephalic vasomotor responses would enhance acquisition of voluntary and biofeedback control of cephalic vasomotor response. Four groups were given discrimination training to detect either constriction, dilation, both constriction and dilation, or given false feedback. All groups were then given biofeedback training in constriction. All groups were assessed on discrimination accuracy, acquisition of biofeedback control of constriction, and voluntary control of dilation and constriction. The results indicated that discrimination of cephalic vasomotor responses can be learned and that this skill facilitates the acquisition of biofeedback and voluntary control of vasomotor responses. This facilitation occurs only if discrimination training is given for the specific response to be learned. The data suggest that discrimination of the relevant response is a necessary but not sufficient condition for acquisition of voluntary control in biofeedback learning.     

Age- and training-related changes in the collagen metabolism of rat skeletal muscle

Summary The effects of ageing and life-long endurance training on the collagen metabolism of skeletal muscle were evaluated in a longitudinal study. Wistar rats performed treadmill running 5 days a week for 2 years. The activities of collagen biosynthesis enzymes, prolyl-4-hydroxylase and galactosylhydroxylysyl glucosyltransferase, were highest in the muscles of the youngest animals, decreased up to the age of 2 months and from then on remained virtually unchanged. The enzyme activity in young animals was higher in the slow collagenous soleus muscle than in the rectus femoris muscle. The enzyme activity in the soleus muscle was higher for older trained rats than older untrained rats. The relative proportion of type I collagen increased and that of type III collagen decreased with age, suggesting a more marked contribution by type I collagen to the agerelated accumulation of total muscular collagen. The results show that collagen biosynthesis decreases with maturation and that life-long endurance training maintains a higher level of biosynthesis in slow muscles.