摘要:

Goats were kept on either high (274 mmol day‐1) or low (68 mmol day‐1) sodium intake during pregnancy, lactation, and anoestrus. High salt (HS) animals had about three times greater renal Na excretion than low salt (LS) animals, but the differences in plasma volume, protein concentration, and haematocrit were generally not significant. Angiotensin II (All) was infused intravenously for 28‐min periods in doses of 0.30, 0.75, or 1.00 nmol min‐1. The increase in mean arterial blood pressure (MAP) during All infusions was greater in HS than in LS goats, but became attenuated in all animals during the course of the pregnancy. In LS goats the MAP rise was smaller in late pregnancy than during lactation and anoestrus. In HS goats the rise in MAP was exaggerated in early pregnancy and was similar to lactation and anoestrus values in late pregnancy. During lactation and anoestrus the goats showed similar MAP increase in response to All infusions. The pulse pressure was greater during All infusions performed in early pregnancy, lactation and anoestrus than in late pregnancy. Cardiac arrhythmias were noted during All infusions, most frequently during lactation and in HS goats in early pregnancy. The results show that a moderately elevated sodium intake causes a significantly higher MAP increase in response to All infusions during pregnancy. This abolishes the reduction of the MAP increase to All infusions during late pregnancy as compared to anoestrus; a phenomenon which is observed in goats on a low sodium

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1987.tb08042.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Young SHR and WKY rats were compared, first, concerning sodium (Na) appetite during ‘rest’, mild social stress and ACTH injections, second, concerning the diurnal patterns of water intake, urine output, mean arterial pressure (MAP) and heart rate (HR) while on various Na diets: 0.5 mmol Na (LNa), 5 or 12–13 mmol Na (CNa), 50 (HNa) or 120 mmol Na (vHNa) per 100 g food. Sodium appetite and water intake were about 50% higher in SHR than in WKY (4–4.5vs2.5–3 mmol Na per 100 g body wt day‐1)‐It was modestly increased by both social stress and ACTH, and more so in WKY, thereby approaching that in SHR. Concerning the various Na diets and their influences, daytime resting MAP was modestly lowered in LNaSHR and slightly increased in vHNaSHR compared with CNaSHR but largely equal in all WKY groups. Food‐water consumption was concentrated to the active night period, but even high Na‐water intakes caused no signs of sustained hypervolaemia, because each intake bout was in both SHR and WKY eliminated by urine within 30–40 min. However, particularly the vHNa diet in SHR also increased the frequency of drinking, and each bout caused transient, evidently neurogenic MAP and HR increases which occurred too rapidly to be consequences of blood volume expansion. As a result, the diurnal MAP‐HR patterns in SHR varied markedly with the Na diets, in vHNa group resulting in considerably raisedaveragediurnal MAP levels even though resting daytime MAP was here nearly the same as in CNaSHR. These findings illustrate how largely continuous diurnal recordings are needed to judge correctly the relationships between, for example, Na intake, volume equilibrium and MAP. Finally, the relevance of these results in rats for also judging the control of Na balanc

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1987.tb08043.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

The electromyographical (EMG) activity was studied during voluntary flexion movements of the trunk in erect standing man. The movements were performed at maximal velocity with successively increasing amplitude to cover the whole range of motion. The EMG activity was recorded from agonist‐antagonist pairs of muscles at the ankle, knee, hip and trunk. The angular displacements at the corresponding joints were recorded using a Selspot optoelectronic system. The duration of initiating activity in prime movers (rectus abdominis and rectus femoris) as well as time to onset of activity in muscles braking the primary movement (erector spinae, gluteus maxims and hamstrings) were highly correlated with amplitude, duration, peak velocity and time to peak velocity of the movement (r = 0.59–0.91). The corresponding correlations for peak acceleration and deceleration of the movement were low (r = 0.03–0.38), indicating that acceleration and deceleration of a movement was not coded in the temporal aspects of the EMG. Onset of activity in rectus abdominis and rectus femoris as well as an early appearing burst of activity in vastus lateralis were invariant in relation to start of movement over the whole movement range. In the initial phase of a fast trunk flexion, activity in tibialis anterior appeared successively earlier with increasing movement amplitude. This resulted in a changed order of activation for the muscles from proximal to distal (rectus abdominis first) to distal to proximal (tibialis anterior first). Two different forms of associated postural adjustments are present during a fast trunk flexion, one early fast knee flexion and a later slower angle extension. Prior to knee flexion, no activity was recorded from muscles flexing at the knee implying that some other force must create a flexing torque around the knee. It is suggested that activity in rectus abdominis initiating the primary movement also initiates knee flexion through the upward pulling of pelvis. This would be possible since rectus femoris stabilizes the pelvis in relation to the leg, allowing the force in rectus abdominis to be transmitted below the hip joint and act extending around the ankle joint. However, when tibialis anterior is activated it stabilizes the shank which in turn will cause a knee flexion controlled by a lengthening contraction in vastus lateralis. During the subsequent ankle extension activity appears in lateral gastrocnemius and soleus causing the associated postural adjustment at the ankle. It can be concluded that activation of postural muscles prior to prime mover muscles is not always necessary. The term linked postural adjustments is proposed for the class of associated movements where activation of prime movers causes both the primary movement and the postural adjustment thus minimizing the perturbation of the equili

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1987.tb08044.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

In this study of human locomotion we investigate to what extent the normal frequency and amplitude of leg movements can be modified voluntarily at different constant velocities, and how these modifications are accomplished in terms of changes in duration and length of the support and swing phases of the stride cycle. Eight healthy male subjects performed walking and running on a motor‐driven treadmill at speeds ranging from 1.0 to 3.0 m s‐1(walking) and 1.5 to 8.0 m s‐1(running), respectively. At each speed the subjects walked and ran with: (i) normal stride frequency; (2) the highest possible stride frequency, and (3) the lowest possible stride frequency. Time for foot contact was measured with a special pressure transducer system under the sole of each shoe. At all speeds of walking and running it was possible to either increase or decrease the frequency of leg movements; that is, to decrease or increase stride cycle duration. The range of variation decreased with increasing speed. The mean overall stride frequency range was 0.41 (low frequency walk 1.0 m s‐1)‐3.57 Hz (high‐frequency run 1.5ms‐1). Stride length ranged 0.40 (high frequency walk 1.0 ms‐1)‐5.00 m (low frequency run 6.0 m s‐1). At normal frequency the overall ranges of stride frequency and length were 0.83–1.95 Hz and 1.16–4.101m, respectively. The stride frequency increased with speed in low frequency walking and running (as in normal frequency) and decreased in high frequency, despite the effort to maintain extreme frequencies. Only in high frequency walking could the stride frequency be kept approximately constant. Stride length increased with speed in all situations, except for low frequency running, where a levelling off occurred at approximately 6 m s‐1. A decrease was observed in support duration with speed, except in high frequency running where it was kept approximately constant (0.12–0.145). Support length showed a total range of 0.19–1.62 m. The longest support length was observed in low frequency walking (all speeds). In normal and high frequency support length increased with speed (in normal frequency up to 1. 10–1.20 m in both walk and run). Thus, locomotion over a wide range of constant velocities can be achieved by different combinations of durations and amplitudes of the stride cycle and its different phases. The normal combination represents a compromise allo

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1987.tb08045.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

We have analysed tissue cyclic 3'5′‐adenosine monophosphate (cAMP) concentration in different fractions of the cat's small intestinal mucosa during secretion elicitedin vivoby four different secretagogues: cholera toxin (administered intraluminally), vasoactive intestinal polypeptide (VIP; given i.a.), arachidonic acid (AA; administered intraluminally) and 5‐hydroxytryptamine (5‐HT; given i.a.). Cholera toxin was found to increase cAMP concentration in the villi but not in the crypts. The VIP, AA and 5‐HT did not influence tissue cAMP concentration despite a profuse net fluid secretion. Hexamethonium inhibited secretion elicited by cholera toxin and AA but did not significantly influence tissue cAMP concentration. There is strong evidence for the view that villus and crypt regions of the small intestinal mucosa have different functions, secretion taking place in the crypts and absorption in the villi. However, the lack of cAMP increase in the crypts reported in this study suggests that cholera toxin in this model does not reach the crypts. The results are not in agreement with a role for cAMP in mediating secretion from the crypts, but are compatible with a role of cAMP in inhibiting absorption in the villi. It is suggested that the observed fluid secretion from the crypts elicited by cholera toxin, AA and 5‐HT is to a major part mediated by intramural enter

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1987.tb08046.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

The effects of human serum orosomucoid (normal serum concentration 0.7–1.0 g l‐1) on capillary permeability were investigated in 12 isolated maximally vasodilated rat hindquarters perfused with bovine serum albumin (50 g l‐1) in modified Tyrode. Measurements were made of capillary filtration coefficient (CFC), permeability surface area product (PS) for vitamin B12and isogravimetric clearance of radiolabelled albumin (Cla1b). The results were compared with those obtained using perfusates without addition of orosomucoid (‘albumin group’) or perfusates containing horse serum (‘serum group’). Clearance of albumin was almost four‐fold higher in the albumin than in the serum group, 0.0895 ± 0.0066 (n= 12) and 0.0252 ± 0.016 ml min‐1per 100 g (n= 18), respectively, while intermediate Cla1bvalues were obtained with human orosomucoid in the perfusate (>0. 1 g l‐1), 0.0436 ± 0.0034 ml min‐1per 100 g) (n= 8). These changes in Cla1bwere not accompanied by any differences in CFC or PS. We conclude that orosomucoid is one of the components in serum (besides albumin) needed for the maintenance of normal permselectivity of the capillary walls of rat skeletal muscle. Alternatively, human orosomucoid is structurally related to other substances exer

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1987.tb08047.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1987.tb08048.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1987.tb08049.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY