摘要:

Healing of the partially ruptured rat gastrocnemius muscle was studied correlating electromyographical findings with morphological changes. Fibrillation potentials and positive sharp waves were seen both proximal and distal to the injury 7 days after the injury and disappeared in the proximal part by day 14 and in the distal part by day 21. Late components of motor action potential were observed from day 14 onwards. Denervation was mainly myogenic, i.e. caused either by rupture of myofibres, whence the abjunctional stump lost its contact with the neuromuscular junction on the adjunctional stump, or by necrosis of the segment of the ruptured myofibre lying underneath the neuromuscular junction. Lesser extent of denervation was neurogenic, i.e. caused by damage to intramuscular nerve fibres. The reinnervation occurs either by regeneration of the necrotized myofibres, by regeneration of the severed nerves, or by collateral innervation of new neuromuscular junctions in the abjunctional stumps. The present study indicates that electromyography may be useful in the diagnosis and follow‐up of skeletal muscle injurie

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1991.tb09179.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The aim of this study was to investigate whether the mean power frequency of the electromyogram of the knee extensors was force and/or muscle fibre‐type dependent. Ten female subjects performed a gradually increasing static knee extension (5 seconds duration) using an isokinetic dynamometer. Electromyogram‐signals were obtained from the vastus lateralis, vastus medialis and the rectus femoris muscles. The torque signal and the three electromyogram signals were recorded on a tape recorder. From the electromyogram recordings the mean power frequency and the signal amplitude were determined. Muscle biopsies were later obtained from the right vastus lateralis and stained for alkaline and acid mATPase for the determination of fibre‐type proportion and areas.Both the mean power frequencies and the signal amplitudes of the three knee extensors were positively torque dependent. Furthermore it was found that the fibre type proportion and the regression coefficient of the torque (%)‐mean power frequency relationship were positively correlated. Also a negative correlation existed between the type‐1 (%) proportion and the intercept of the individual torque (%)‐mean power frequency relationships. In contrast to proposed models of the electromyogram signal no correlation was found between the mean power frequency and the

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1991.tb09180.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The effect of a reduction in arterial oxygen content, equivalent to acute exposure to an altitude of 2300 metres above sea level, on myocardial blood flow and oxygen and lactate exchange was studied by coronary sinus catheterization in 12 healthy men. Measurements were made at rest, during atrial pacing and during submaximal and maximal exercise both breathing air and breathing 15% oxygen (hypoxia). Coronary sinus blood flow was measured by thermodilution and the possibility of a simultaneous uptake and release of lactate by the heart was calculated using intravenous infusion of14C lactate. At all levels of cardiac power output myocardial oxygen consumption was the same during hypoxia as during air breathing. At rest this was achieved entirely by a more complete extraction of oxygen from the coronary blood, during maximal exercise entirely by a greater coronary sinus blood flow, while at intermediate levels of cardiac power output a combination of these mechanisms prevailed. At rest and during submaximal work myocardial lactate extraction was lower with hypoxia than air breathing suggesting a change in myocardial redox state, while the14C lactate data suggested no significant lactate release or possibly limited areas with some lactate production. During maximal exercise, however, there was no difference in myocardial lactate net extraction between hypoxia and air breathing, which together with the greater blood flow suggests that the heart has a ‘coronary flow reserve’ permitting maximal exercise at moderate altitude without anaerobic myocardial metabol

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1991.tb09181.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The specific accumulation of the K+‐analogue TI+(201Tl+) in muscle after intramuscular injection was analysed by gamma spectrometryin vivoof rat hamstring muscles. A mixture (0.1ml) of201Tl+(thallous+chloride‐) and99mTc‐pertechnetate‐ (Na+pertechnetate‐) was given, by which99mTc‐pertechnetate‐served as a reference substance with negligible intracellular accumulation. After 30 min 8.9 ± 5.8% of injected99mTc‐pertechnetate‐remained in the muscle and 49+10% of201Tl+(±SD,n =18). The difference between201Tl+and99mTc‐pertechnetate‐ at 30 min was taken as a measure of the intracellular201Tl+accumulation, which was 40% of the initial amount of201TI+. The half‐time of the calculated intracellular201TI+accumulation was 4.9+1.9 min. In the presence of ouabain (1.0 mM in the injectate) the intracellular201Tl+accumulation was 25+10% (n =7), that is ouabain decreased the intracellular201Tl+accumulation by 38% (P =0.0035). Non‐radioactive TI+(1.0 mM TI‐acetate in the injectate) inhibited the uptake by 35% (P= 0.0013). Ouabain did not significantly affect the half‐time for the Tl+uptake. An increase in [K+] of the injectate from 0 to 5 mM had no significant effect. Insulin (0.2 units in the injectate) had no effect.It is concluded that the specific TI+‐accumulating properties of muscle fibres can be studied with the presentin vivotechnique, which can provide information about the Na‐K‐ATPase activity and th

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1991.tb09182.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Male volunteers were exposed to +10° C ambient temperature for 2 hours while they were sitting undressed. The levels of endothelin‐1 and atrial natriuretic peptide were determined by radioimmunoassays. Control samples were obtained at thermoneutrality. The cold exposure resulted in lowering of the mean skin temperature (from 31.2± 0.3°C‐22.6 ± 2.5°C, mean ± SEM), which indicates that a marked vasocon‐striction took place, as well as a decrease of the body heat content (by 11.2 ± 0.7 kJ kg‐1). However, plasma endothelin‐1 levels did not change significantly during the exposure. Thus circulating endothelin‐1 does not seem to be responsible for the vasoconstriction associated with cold air exposure. The plasma atrial natriuretic peptide levels exhibited a slight increase towards the end of the cold exposure. This finding is in accord with the notion that atrial natriuretic peptide might contribute to the diuresis frequently ob

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1991.tb09183.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

We have examined the subcellular distribution of galanin‐like immunoreactivity, neuropeptide Y‐like immunoreactivity and the catecholamines noradrenaline and adrenaline in the adrenal medulla from guinea‐pigs. By differential centrifugation of the adrenal medulla homogenate the neuropeptides as well as the catecholamines sedimented in a 10000 g pellet. This pellet was resuspended and further examined in discontinuous and continuous density gradients. In the discontinuous gradient the catecholamines peaked in the heavy bottom fraction, assumed to contain chromaffin granules. Galanin‐like immunoreactivity and neuropeptide Y‐like immunoreactivity were also enriched in this fraction. However, both neuropeptides showed high levels of sedimentable material also in a fraction of intermediate density. In the continuous density gradient, the sum of sedimentable and soluble catecholamines showed peak values in two fractions corresponding to 1.07 and 1.47m sucrose, respectively. The NA peak in the denser fraction was more pronounced than the corresponding A peak. Galanin‐like immunoreactivity showed only one peak, in the fraction corresponding to 1.07 M sucrose. The data suggest that galanin‐like immunoreactivity and neuropeptide Y‐like immunoreactivity are partly stored with catecholamines in chromaffin granules. However, galanin‐like immunoreactivity and neuropeptide Y‐like immunoreactivity was also found in fractions lighter than those containing the bulk of

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1991.tb09184.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The effects of mammalian gonadotropin‐releasing hormone on ovarian release of progesterone, androgens and estradiol‐17β were studiedin vitroby a superfusion system carried out on follicles of adult femaleRana esculenta, collected at different periods of the annual reproductive cycle.The follicles were superfused with medium alone, pituitary, mammalian gonadotropin‐releasing hormone, or pituitary plus mammalian gonadotropin‐releasing hormone. For follicles obtained in the prereproductive period, pituitary plus mammalian gonadotropin‐releasing hormone increased the estradiol values much more than pituitary alone. In the reproductive period, pituitary alone increased the estradiol values much more than pituitary plus mammalian gonadotropin‐releasing hormone. For follicles obtained in the recovery period, mammalian gonadotropin‐releasing hormone alone stimulated the highest estradiol production, and pituitary plus mammalian gonadotropin‐releasing hormone increased the estradiol values much more than pituitary alone.The results reported here suggest that mammalian gonadotropin‐releasing hormone and/or pituitary have a direct effect on ovarian estradiol secretion, and that this effect varies with the annual

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1991.tb09185.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The effect of angiotensin II (Ang II) was studied on blood flow in the submandibular gland and tongue in male rats. Blood flow changes were determined with laser Doppler flowmetry and Ang II was infused into the common carotid artery before and after i.v. doses (18 nmol kg‐l) of the angiotensin II antagonist saralasin. Angiotensin II (10–60 pmol min‐l) dose‐dependently increased blood pressure and tongue blood flow, whereas glandular blood flow decreased at all of the doses used. After saralasin administration the angiotensin II effects on blood pressure, tongue and glandular blood flow were significantly diminished (glandular blood flow reduction was diminished from 29%‐3%,P<0.005,n =9). However, the responsiveness of these 3 parameters to local infusions with noradrenaline (0.75–3.0 pmol min‐1) was unaffected by saralasin. The dose of saralasin used in the present study did not affect any of the parameters on it's own. Our results show that vascular receptors sensitive to angiotensin II operate in the submandibular gland but not

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1991.tb09186.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Simultaneous recordings of blood flow in the right and left aorta and carotid and coeliac artery were made in the crocodile,Crocodylus porosusat rest and during various stimuli. In resting animals the right aorta and carotid artery flow profiles resembled the recordings obtained in the caiman (Axelssonet al. 1989 a), with an anterograde blood flow throughout the cardiac cycle. As in the caiman, the left aorta flow profile was complex with both anterograde and retrograde blood flow during the cardiac cycle, and a net left aorta blood flow near zero at rest.The coeliac artery blood flow profile did not show the complex pattern seen in the upper aorta, immediately suggesting that most of the coeliac artery blood originates elsewhere. We believe that coeliac artery blood flow in the resting animal derives from the right aorta via the abdominal anastomosis between the two aortas. Feeding induced an increase in the coeliac artery and left aorta blood flow, probably due to a decrease in visceral vascular resistance, and hence coeliac arterial and the left aorta blood pressure, which facilitates blood flow (from right to left aorta) through the foramen of Panizza.During short ‘fright dives’, heart rate fell and there was a decrease in the recorded blood flows: carotid artery blood flow did not decrease to the same extent as the RAo and coeliac artery flow, indicating some capacity for redistribution of blood to the cephalic circuits during diving. Similarly, a near‐unimpaired carotid artery blood flow was maintained after adrenaline injection.Substance P increased the coeliac artery blood flow and produced a right‐to‐left cardiac shunt, probably by construction of the pulmonary va

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1991.tb09187.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The aim of the presentin vivostudy was to investigate in anaesthetized rats, the effects of selective adrenergic agonists and antagonists on basal gastric tone and phasic contractions by the use of a volumetric method. L‐phenylephrine, an alpha‐1 agonist, induced hypertension, bradycardia and a significant gastric relaxation. Clonidine, an alpha‐2 agonist, caused hypotension, bradycardia and a significant gastric contraction and a reduction of the amplitude of phasic contractions. Salbutamol, a beta‐2 agonist, induced a dose‐dependent tachycardia and a significant inhibition of gastric tone whereas prenalterol, a beta‐1 agonist, induced tachycardia without any significant influence on gastric basal tone. Yohimbine, an alpha‐2 blocker, significantly decreased gastric basal tone and reversed the inhibition of phasic contractions induced by clonidine. Prazocine, a selective alpha‐1 blocker, and propranolol, a non‐selective beta‐blocker, had no significant influence on gastric basal tone or phasic contractions.It is concluded that sympathetic inhibition of basal gastric tone in the rat is mediated by alpha‐1 and beta‐2 adrenergic receptors. Activation of alpha‐2 adrenergic receptors significantly increased basal gastric tone and reduced the amplitude of phasic contractions. A blockade of alpha‐2 receptors significantly decreased basal gastric tone and restored the ampli

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1991.tb09188.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY